Revision Notes Chemistry XII

8/11/2019 Revision Notes Chemistry XII

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14. Schottky defect, a stoichiometric orvacancy defect, arises due to missing ofequal number of cations and anions from thelattice and is shown by crystals havingcation and anion of comparable size.

e.g., CsCl, NaCl, AgBr etc. It results indecrease in density.

15. Frenkel defect, a stoichiometric orinterstitial defect, arises when the smaller ion(usually cation) is dislocated from its normalsite to an interstit ial site. It results inincreased conductivity but density of thecrystal remains the same.

16. Impurity defects arise when foreign atomsare present in the lattice site or in theinterstitial site.

e.g.,solid solution of CdCl2-AgCl.

17. In metal excess defect, the anionic sites occupied by unpairedelectrons are called F-centres, which impart colour to thecrystals. It is a non-stoichiometric defect.

18. Doping is the process of introduction of impurity in thesemiconductors to enhance their conductivity. Doping ofelements of group 14 (like silicon, germanium) with electrondeficient elements (i.e., elements of group 13) and electronrich elements (i.e., elements of group15) result in p-type and

n-type semiconductors respectively.

19. Ferromagnetic substances are strongly attracted by theexternal magnetic field because all the domains get orientedin the direction of magnetic field. These substances behaveas permanent magnets.

20. In ferrimagnetic substances,the magnetic moments of thedomains are aligned in parallel and antiparallel directions inunequal numbers, so net magnetic moment is small.

Solutions1. Asolutionis a homogeneous mixture of two

or more substances whose composition canbe varied within certain limits.

2. Mole fractionis the number of moles of onecomponent to the total number of moles ofall the components present in the solution.

The mole fraction of solute,

xn

n n(solute)

(solute)

(solute) (solvent)

=

+It is independent of temperature.

It can be shown, for a given solution, sum ofmole fractions of all the components of asolution is unity, i.e.,

x x xi1 2 ... 1+ + + =

3. Molarity is defined as the number of molesof solute dissolved in one litre or one cubicdecimetre of the solution.

Molarity = Moles of solute

Volume of solution (L)

4. Molality (m) is defined as the number of

moles of the solute per kilogram of thesolvent.

Molality = Moles of solute

Mass of solvent in kg

5. Henrys law states that the partial pressureof the gas in vapour phase (p) isproportional to the mole fraction of the gas (x) in the solution.

Mathematically, it is expressed as

p x or p K xH=

where, KH is called Henrys law constant.

Higher the value of KH at a particulartemperature, the lower is the solubility of thegas in the liquid.

6. Solubility of gases decreases with increase of temperature.This is the reason that aquatic species are more comfortablein cold water rather than in warm water.

7. To avoid bends, as well as, the toxic effects of highconcentrations of nitrogen in the blood, the tanks used byscuba divers are fil led with air diluted with helium(11.7% helium, 56.2% nitrogen and 32.1% oxygen).

8. The pressure exerted by the vapours above the liquid surface

in equilibrium with the liquid at a given temperature is calledvapour pressure.

9. Raoults lawstates that at a given temperature, for a solutionof volatile liquids, the partial vapour pressure of eachcomponent of the solution is directly proportional to its mole

fraction present in solution i.e., p x1 1 and p p x1 1 1= .

For a solution of two components 1 and 2, p p ptotal = +1 2

So, p p x p xtotal = + 1 1 2 2

As we know, x x1 2 1+ = or x x1 21= ,

p p p p x= + 1 2 1 2( )

10. Solutions obeying Raoults law over a wide range ofconcentration are calledideal solutions but that do not arecalled non-ideal solutions.

For positive deviation,

AB interaction < A A or BB interactions

e.g.,CS2+ acetone, acetone +benzene.

For negative deviation,

AB interaction > AA or B B interactions

e.g.,chloroform + acetone, chloroform + benzene.

11. The properties of solutions which depend only on thenumber of solute particles, not on the nature of the soluteparticles are known as colligative properties.

12. Relative lowering in vapour pressure of an ideal solution

containing the non-volatile solute is equal to the mole fractionof the solute at a given temperature.

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x p

p

p p

p2

1

1

1 1

1

=

=

p p

p

W M

W M1 1

1

2 1

1 2

=

13. The difference in the boiling points of thesolution(Tb) and pure solvent (Tb ) is called theelevation of boiling point (Tb). It depends onthe number of solute particles rather than theirnature.

T T Tb b b=

Experimentally, T m T k mb b b = or

wherem =molality = Moles of solute ( ) 1000

Weight of solvent ( )

n

W

and moles of solute = w

m

kb = molal boiling point elevation constantor ebullioscopic constant (unit K kg mol 1 ).

T kb b=

w

m

1000

W

14. Addition of a non-volatile solute results indepression of freezing point (Tf).

Thus, Tf = T Tf f

or T mf = =

k k

w

mf f

1000

W

Where, m = molality and kf = freezing pointdepression constant or cryoscopic constant.

15. The excess pressure which must be applied to a

solution to prevent the passage of solvent into itthrough a semipermeable membrane is calledosmotic pressure.

= CRT

=W RT

VM2

2

16. Isotonic solutions are the solutions having sameosmotic pressure.

17. In case of two solutions of different osmotic pressuresthe solution with higher osmotic pressure is calledhypertonic solution and that with lower osmoticpressure is called hypotonic solution.

18. People taking a lot of salt or salty food experience waterretention in tissue cells and intercellular spaces becauseof osmosis. This resulting puffiness or swelling is callededema.

19. In reverse osmosis, the solvent flows from solution topure solvent, if pressure higher than osmotic pressure isapplied on solution side. It is used for desalination of seawater.

20. Molar masses that are either lower or higher than theexpected or normal values are called abnormal molarmasses.

21. vant Hoff factor ( )i is defined as the ratio of the

experimental value of the colligative property to thecalculated value of the colligative property.

i=Normal (calculated) molar mass

Observed (abnormal) molar mass

or i= Observed colligative property

Calculated colligative property

For electrolytes, i is also introduced in the formula ofrelative lowering of vapour pressure, T Tb, f, and. i.e.,

T ik m T ik mb b f, f= = =iCRT and

p p

pi

=1 Xsolute

Electrochemistry1. An electrochemical cell is a device in which

chemical energy of the redox reaction isconverted into electrical energy.

e.g., galvanic cell like Daniell cell, reactionoccurring in which is

Zn Cu Zn Cu2 2( ) ( ) ( ) ( )s aq aq s+ ++ +

2. While writing a cell, the anode is written on theleft and the cathode on the right. A vertical lineseparates the metal from the metal ion(electrolyte solution) and a double vertical lineindicates a salt bridge which is written betweenthe two half-cells (two electrolytes).

The Daniell cell is represented as

Zn ( ) | Zn ( ) || Cu ( ) | Cu ( )2 + 2 +s aq aq s

3. The electrode potential under the conditions ofunit concentration of all the species in thehalf-cell is called the standard electrodepotential and the electrodes of known potential

is known as reference electrode.e.g.,standardhydrogen electrode (potential of which is takenas zero) and calomel electrode.

4. The potential difference between the two half-cells iscalled the cell potential.

E E Ecell cathode anode =

5. The arrangement of various standard half-cells in order oftheir decreasing values of standard reduction potentials

is called electrochemical series. I f the standardelectrode potential of an electrode is greater than zero,then its reduced form is more stable as compared tohydrogen gas.

Similarly, in case of standard electrode potential beingless than zero (negative value), hydrogen gas is morestable than the reduced form of the species.

6. Nernst equationis that equation which gives the relation

between electrode potential and concentration of metal

ions.

E E RT

nF

M

MM M M M nn n( (

ln [

]+ += +/ ) / )

]

[

For a general electrochemical reaction of the type

aA bB cC dDne

+ +

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The Nernst equation can be written as

E E RT

nFQ( ce ll ) (c el l)=

ln

= E RT

nF

C D

A B

c d

a b(cell)

ln[ ] [ ][ ] [ ]

In general, at equilibrium

E RT

nFKc(cell)

2.303 = log

7. Under standard conditions, the emf of a cell isrelated to the Gibbs free energy rG as

rG nFE = ( )cell

8. The inverse of resistivity is called the conductivity orspecific conductance, . Its units are m orSm .

k Cell constant=

G

Rwhere,G

l

a=

9. Molar conductivity (m) of a solution is the

conductance of that volume of solution containingone mole of electrolyte, kept between two electrodeshaving unit length between them and large crosssectional area so as to contain the electrolyte.

The unit of m will beW m mol1 2 1 orSm mol2 1 .

mM

= 1000

10. Conductivity always decreases with decrease inconcentration (that is, with dilution) of both thestrong and weak electrolytes. This is due to the factthat the number of ions that carry current in a unitvolume of solution always decreases with decreasein concentration. Molar conductivity increases withdecrease in concentration (that is, with dilution). Thisis because the total volume V of the solutioncontaining one mole of electrolyte also increases.

11. Kohlrausch law of independent migration of ionsstates that l imiting molar conductivity of anelectrolyte is the sum of the individual contributionsof the cation and the anion of the electrolyte.

In general, if an electrolyte produces + cations and anions,

m = ++ +

12. Electrolytic cells are those cells in which electrical

energy is used to carry out non-spontaneouschemical reactions and the reaction takes place in anelectrolytic cell is called electrolysis.

13. Faradays first law states that the amount ofchemical reaction occurring at an electrode bypassing current is proportional to the quantity ofelectricity passed through the electrolyte (in solutionor in molten state).

w = Zit

where, Z= electrochemical equivalent or Faradaysconstant

14. Faradays second law states that when the samequantity of electricity is passed through differentelectrolytes, the amounts of different substancesformed are proportional to their chemical equivalentweights.

W

E

W

E

W

E1

1

2

2

3

3

= = = ....

where W is the mass of substance and E is itsequivalent weight.

15. A battery contains one or more than oneelectrochemical cells connected in series. It may bea primary battery (non-chargeable battery like drycell such as Leclanche cell) or secondary battery(rechargeable) like lead storage battery.

16. When the lead storage battery is in use (discharging),

the cell reactions are

AnodePb ( ) SO ( ) PbSO ( ) 242

4s + + aq s e

Cathode

PbO SO 4H2 42( ) ( ) ( )s aq aq e+ + + + 2

PbSO 2H O4 2( ) ( )s + l

The overall reaction of the cell is written as

Pb ( ) PbO ( ) 2H SO ( )2 2 4s s aq+ +

2PbSO ( ) 2H O( )4 2s + l

17. A fuel cell is a galvanic cell in which chemicalenergy from combustion of fuels is converted intoelectrical energy.

18. One of the most successful fuel cells uses thereaction of hydrogen with oxygen to form water. Itwas used for providing electrical power in Apollospace programme.

The electrode reactions are

Cathode O ( ) 2H O ( ) 42 2g e+ +

l 4OH ( )aq

Anode 2H ( ) 4OH ( ) 4H O( ) 42 2g aq e+ +

l


2H ( ) O ( ) 2H O ( )2 2 2g g+ l

Fuel cells are pollution free, produce electricity with

an efficiency of about 70% and never become dead

due to continuous supply of fuel.

19. Corrosion is an electrochemical process in which ametal oxide or other salt of the metal forms a coatingon the metal surface. The rusting of iron, tarnishingof silver surface, surface of copper and bronzeturning green are some of the examples ofcorrosion.

20. The anode and cathode reactions occurring in theprocess of rusting are

Anode 2Fe( ) 2Fe 42+s e +

E(F e / Fe)2

0.44 V+ =

Cathode O ( ) 4H ( ) 42 g aq e+ + + 2H O( )2 l ;

EH | O | H O2 2

1.23 V+ =


2Fe( ) + O ( ) 4H ( )2s g aq+ +

2Fe ( ) 2H O( )2+ 2aq + l E(cell) 1.67 V =

Hydrated ferric oxide (Fe O H O)3 4 2x in the form ofrust is produced, when ferrous ions produced arefurther oxidised by atmospheric oxygen.

2Fe ( ) 2H O ( ) 1

2

O ( )2 2 2+ + + aq l g

Fe O ( ) 4H ( )2 3 s aq+ +



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Chemical Kinetics1.

Thespeedor therate of a chemical reactioncanbe defined as the change in concentration ofreactants or products in unit time.

Its units are concentration time 1 or mol L s1 1 .

2. Theaverage rate of reaction is the appearance ofproduct or disappearance of reactants over a longtime interval.

rav

= =

[ ] [ ]R

t

P

t

3. Reaction rate, at a particular moment of time iscalled instantaneous rate of the reaction

rinst

=d R

dt

[ ]=

d[P]

dt

As t 0Instantaneous rate= Average rate

4. Rate of a chemical reaction depends upon theexperimental conditions like concentration of one ormore reactants (pressure in case of gases),temperature, catalyst and surface area of thereactants.

5. Rate law is the expression in which the reactionrate is given in terms of molar concentration ofreactants with each term raised to some power,

which may or may not be same as the stoichiometriccoefficient of the reacting species in a balancedchemical equation. Rate law for a chemical reactioncan not be decided from the balanced chemicalequation, i e. ., theoretically. It has to be determinedexperimentally.

6. The sum of the powers of the concentration of thereactants in the rate law expression is called the orderof that chemical reaction.

7. The number of reacting species (atoms, ions ormolecules) taking part in an elementary reaction, whichmust collide simultaneously in order to bring about achemical reaction is called molecularity of a reaction.

8. Order can be zero or have fractional value but

molecularity of a reaction can not be zero or anon-integer. It is always an integer.

9. Rate constant is the rate of chemical reaction whenconcentration of each reactant is unity. The rateconstant is also called the specific reaction rate.

10. Fornth order reaction, units of k = (mol L )1 n, where,n

=order of reaction.

11. Table summarises the mathematical features ofintegrated laws of zero and first order reactions.

12. For a chemical reaction with rise in temperature by10, the rate constant is nearly doubled.

13. Temperature coefficient is the ratio of rateconstant at temperature 308 K to the rate constantat temperature 298 K.

Temperature coefficient

= Rate constant at 308(298+10) K

Rate constant a

k

k t 298 K

14. The temperature dependence of rate of a chemicalreaction is expressed by Arrhenius equation.

k Ae E RT= a/

where, A is the Arrhenius factor or the frequencyfactor, also called pre-exponential factor.

In lnk E

RTAa=

+

The plot of ln k vs 1/Tgives a straight line.

logk

k

E

. R

T T

T Ta2

1

2 1

1 22 303=

15. Activation energy (Ea) is the extra energy contained

by the reactant molecules that results into effective

collision between them to form the products.16. Threshold energy is the minimum energy which the

colliding molecules must have for effective collision.

Effective collisions are those collisions which lead tothe formation of product molecules.

17. According to collision theory,

Rate =ZABe E / R T a

where, ZAB = collision frequency of the reactants AandB.

e E RTa =fraction of molecules with energies equal to orgreater thanEa.


Integrated Rate Laws for the Reactions of Zero and First Order

Order ReactionType DifferentialRate Law IntegratedRate Law Straight Line Plot Half-life Units of k

0 R P d R dt k[ ]/ = kt R R= [ ] [ ]0 [ ]R vs t [ ] /R k0 2 Conc. time1 or

mol L 1 1s

1 R P d R dt k R[ ]/ [ ]= [ ] [ ]R R e kt= 0 or

kt = In {[ ] / [ ]}R R0

In [ ]R vs t In 2/k time 1 or s 1


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Surface Chemistry1.

The process in which molecular species areaccumulated at the surface rather than in the bulk ofa solid or liquid is termed as adsorption. e.g., watervapours on silica gel; H2, O2, NH3 on activatedcharcoal.

2. Solids, particularly in finely divided state, have largesurface area therefore metals in finely divided stateetc., acts as good adsorbents.

3. Adsorption is an exothermic process i.e., H

adsorption is always negative. Since, the moleculesof the gas are held on the surface of the solidadsorbent hence entropy decreases (because theirfreedom of movement become restricted),i.e., S isalso negative.

4. The adsorption in which accumulation of gas on thesurface of a solid occurs on account of weak vander Waals forces is called physical adsorption orphysisorption. It is also called van der Waalsadsorption.

5. The adsorption in which gas molecules or atoms areheld to solid surface by chemical bonds is calledchemical adsorption or chemisorption. Chemicalbonds are responsible for the adsorption inchemisorption, thus it is highly specific in nature andresults in the formation of only monomolecular layer.

6. Freundlich gave the following relationship betweenx/m and p at particular temperature.

xm

k p n= 1/

where, m = mass of adsorbent,

x = mass of gas adsorbed on mass m,

p = pressure,

k and n = constant, n = integer

or log log 1

logx

mk

np= +

When log x/m is plotted with log p, a straight line isobtained with slope 1/n and intercept on y-axis isequal to log k.

7. A substance that alters the rate of chemical reactionwithout itself undergoing any chemical change, is

known as catalyst and this process is known ascatalysis.

8. The phenomenon in which reactants and catalyst arepresent in the same phase (i.e., liquid or gas ) isknown as homogeneous catalysis.

9. The phenomenon in which the reactants and catalystare in the different phases, is known as hetero-geneous catalysis.

10. When the catalytic reaction depends upon theporous structure of catalyst and the size of thereactant and the product molecules, the reaction isknown as shape-selective catalysis.

11. Zeolites are microporous aluminosilicates. General

formula is M zx/n x y[(AlO ) (SiO ) ] H O2 2 2 . e.g., ZSM-5converts alcohols directly into gasoline (or petrol a

mixture of hydrocarbons) by dehydrating them.

12. Enzymesare biochemical catalysts that catalyse thereactions occurring in living beings. These are highlyspecific in nature and work well only at a specific pH.

13. A colloid is a heterogeneous system in which onesubstance is dispersed (dispersed phase) as veryfine particles in another substance calleddispersionmedium.

14. Colloidal sols directly formed by mixing substanceslike gum, gelatine, starch, rubber, etc., with asuitable liquid (the dispersion medium) are calledlyophilic sols. These sols are also called reversiblesols or protective colloids (as they protectlyophobic sols) from coagulation. These sols arequite stable and cannot be coagulated.

15. Substances like metals, their sulphides etc., whensimply mixed with the dispersion medium do notform the colloidal sol. Their colloidal sols can beprepared only be special methods. Such sols arecalled lyophobic sols. These sols are also calledirreversible sols. Lyophobic sols need stabilisingagents for their preservation.

16. Multimolecular colloids are formed by theaggregation of a large number of atoms or smallermolecules of a substance when they aggregatetogether to form species having size in the colloidalrange, e.g., sulphur sol consists of particlescontaining a thousand or more of S 8 sulphurmolecules.

17. Macromolecules in suitable solvents form solutionsin which the size of the macromolecules may be inthe colloidal range. Such colloids are calledmacromolecular colloids.

These colloids are quite stable and resemble withtrue solutions in many respects, e.g., naturallyoccurring macromolecules such as starch, cellulose,proteins and enzymes.

18. There are some substances which at lowconcentrations behave as normal strong electrolytes,but at higher concentrations exhibit colloidalbehaviour due to the formation of aggregates. Theaggregated particles thus formed are called

micelles. These are also known as associatedcolloids.

The formation of micelles takes place only above aparticular temperature, called Kraft temperature( )Tkand above a particular concentration, called CriticalMicelle Concentration(CMC).

19. Preparation of colloidal sol of non-metal.2H S SO 3S 2H O2 2 2

(Sol)+ +

Preparation of colloidal sol of metals.

2AuCl 3HCHO 3H O 2Au3 2(Sol)

+ + + +3HCOOH 6HCl

20. Peptisation is the process of converting freshly

prepared precipitate into colloidal sol by shaking itwith the dispersion medium in the presence of smallamount of electrolyte. The electrolyte added is calledthe peptising agent.



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21. Purification of colloidal solution by diffusion through asuitable membrane is called dialysis. The apparatusused for this purpose is called dialyser.

22. When light falls on sol, sol absorbs the light andscatter it. This phenomenon of scattering of light iscalled Tyndall effect. The illuminated path of lightpassing through the colloids is called Tyndall cone.

23. The process of settling of colloidal particles is calledcoagulation or precipitation of the sol. It is done byelectrophoresis, boiling, mixing two oppositelycharged sols or by additing electrolytes.

24. Hardy Schulze RuleAccording to this rule, thegreater the valence of the flocculating ion added, thegreater is its power to cause precipitation.

The order of coagulating power of the cations is

Al Ba Na .3 2+ + +> >

The order of coagulating power of the anions is[Fe(CN) ]6

4 > PO SO Cl43

42 > > .

25. Emulsions are formed when both the dispersedphase and dispersion medium are liquids in acolloidal system.

26. Oil dispersed in water type - milk, vanishingcream.

Water dispersed in oil type - butter and cream.

27. It is possible to cause artificial rain by throwingelectrifieds and or spraying a sol carrying chargeopposite to the one on clouds from an aeroplane.

28. Blood is an albuminoid suspended in water, whichimplies that blood is a colloid. Alum and FeCl3solution stop bleeding due to coagulation.

29. Colloidal sol adsorbs one of its own ion from thesolution preferentially and gets charged. Thischarge attracts ions of opposite charge from thesolution and forms an electrical double layer. This is

calledHelmholtz electrical double layer.

General Principles andProcessesofIsolation ofElements

1. The substance in the form of which a metal(or element) occur in nature, is called the mineral ofthe element.

2. The minerals from which a metal can be extracted

conveniently and profitably are called ores.e.g.,bauxite is an ore of aluminium.

3. Aluminium is the most abundant metal while oxygenis the most abundant element in the earths crust.

4. The substance which is added in the ore to convertnon-fusible gangue to fusible compound, (called slag)is called flux.

The flux may be acidic (like SiO2) or basic (like CaO,MgO etc).

5. Froth floatation process is used to concentratesulphide ore because of the preferential wetting of orewith pine oil. Here collectors (like pine oil, xanthatesetc) enhance the non-wettability of mineral particles,while froth stabilisers like cresols, aniline etc, stabilisethe froth.

6. Leaching is used when ore is soluble in somesuitable solvent while impurities remain insoluble e.g.,leaching of alumina from bauxite by Baeyers process.

7. Gold or silver ore is leached with dilute NaCN solutionin the presence of air to give a metal complex, fromwhich metal is displaced by zinc. This process iscalled cyanide process.

4 8CN 2H O 4[ (CN) ] 4OH2 2M M+ + + +

2[ CN) Zn [Zn(CN) 22 42

MetalM M] ] + +

8. The process of heating of metal ore in the absence ofair is called calcination. by calcination, ore isconverted into oxide.

CaCO CaO + CO3 2

9. The process of heating of metal ore below itsmelting point in the presence of air is calledroasting. By roasting, ore is converted to oxide.

2ZnS + 3O 2ZnO + 2SO2 2

10. The process of reduction of metal oxide into crudemetal by C or CO is called smelting.

11. According to Ellingham diagram, for a reductionprocess to be feasible the sum of G of the tworeactions (oxidation of reducing agent andreduction of metal oxide) should be negative.

12. Zone refining is based on the principle that theimpurities are more soluble in the melt than in thesolid state of the metal. Metals like, Si, Ge, Ga, Betc are refined by this process.

13. Vapour phase refining is based on the principlethat the metal is first converted into its volatilecompound and collected elesewhere. Then it is

decomposed to give pure metal. e.g.,(i) Monds process is used to refine nickel.

Ni 4CO Ni(CO)Impure

330-350K

Volatilecompou

4+

nd

450-470K

PureNi 4CO +

(ii) van-Arkel process is used to refine zirconiumand titanium.

Zr 2I ZrI Zr 2IImpure Metal iodide Pure

2 4 2+ +

14. Chromatography is the most advanced techniqueused for separation or metallurgical purposes.

It is based on the principle that differentcomponents of a mixture are adsorbed differentlyon an adsorbent.



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p-Block Elements1. Molecular nitrogen comprises about 78% by

volume of earths atmosphere. It exhibitsanomalous properties due to its smaller size,high ionisation enthalpy, high electronegativityand absense of d-orbitals.

2. Nitrogen has a unique ability to form p p

multiple bonds with itself and with other atomslike C and O. Thats why it exists as N 2 moleculewith a triple bond and has high bond enthalpy.

3. Heavier members of nitrogen family form p d bond and show catenation due to their highsingle bond energy.

4. Nitrogen can not form d-p bond due toabsence of d- orbitals so it can not expand itscovalency beyond four as the heavier memberscan e.g., R3P O or R3P CH2 (R= alkylgroup).

5. Reducing character of hydrides of nitorgenfamily increases down the group due todecrease in bond dissociation enthalpy.

6. Basic characterand bond anglein the hydridesof nitrogen family decreases down the group,

i.e.,

[NH PH AsH SbH BiH ]3 3 3 3 3> > >

7. Boiling point of NH3 is more than PH3 due toH-bonding. After PH3 boiling point increasesdown the group.

8. Ammonia is manufactured by Habers process.

N ( ) 3H ( ) 2NH ( );2 2 3g g g+

fH

= 46.1 kJ / mol

The optimum condition for the production ofammonia are a pressure of200 105 Pa (about200 atm), a temperature of ~700 K and the useof a catalyst such as iron oxide with smallamount of K O2 and Al O2 3to increase the rate ofattainment of equilibrium.

Earlier i ron was used as a catalyst withmolybdenum as a promoter.

9. NH3 forms a number of complexes with metal

ions such asCu , Ag2+ + etc.

Ag ( ) 2NH ( ) [Ag(NH ) ] Cl( )3 3 2+ + aq aq aq

Cu ( ) 4NH ( ) [Cu(NH ) ] ( )2 3 3 42

Blue Deep blue

+ ++aq aq aq

10. Because of the presence of odd number ofvalence electrons NO2 dimerises to give N O2 4

N O2 4 with even number of electrons. The covalency of NinN O2 4 is 3 and inN O2 5 is 4.

11. Nitric acid is manufactured by Ostwalds process andinvolves the following steps.

4NH ( ) 5O ( ) 4NO3 2Pt/Rh gauge

500K, 9 barg g+ ( )+6 2g H O( )l

2 NO( ) O ( ) 2 NO ( )2 2g g g+

3NO ( ) H O( ) 2HNO ( ) NO( )2 2 3g l aq g+ +

12. Nitric acid being a strong oxidising agent oxidisesmostly metals (except gold and platinum) andnon-metals. Its oxidisesCutoCu2+ , iodine to iodic acid,C toCO2, S to H SO2 4and P to phosphoric acid( )H PO3 4 .

13. White phosphorus (P4) is more reactive than othersolids due to less angular strain. It dissolves in boilingNaOH solution in an inert atmosphere giving PH 3.

P 3NaOH 3H O PH 3NaH PO4 2 3 2 2+ + +

14. PH3

(phosphine) gets absorbed in CuSO4

or mercuricchloride solution to form corresponding phosphides.

3CuSO 2PH Cu P 3H SO4 3 3 2 2 4+ +

3HgCl 2PH Hg P 6HCl2 3 3 2+ +

15. PCl3 hydrolyses in the presence of moisture giving

fumes of HCl.

PCl 3H O H PO 3HCl3 2 3 3+ +

16. In solid state PCl5 exists as ionic solid [PCl ]4+ [PCl ]6

where the cation [PCl ]4+ is tetrahedral and anion [PCl ]6

is octahedral.

17. All oxo acids of P contain at least one P O== bond and

one P OH bond. In these oxoacids, the H-atom of OH

group is ionisable and cause the basicity. The acidswhich contain P H bond, have strong reducingproperties.

4 AgNO 2H O H PO3 2 3 2+ + + +4Ag 4HNO H PO3 3 4

18. When H PO3 3 (phosphorus acid) is heated, itdisproportionate to give phosphoric acid and phosgenegas.

4H PO 3H PO PH3 3 3 4 3 +

19. Electron gain enthalpy of oxygenis less negative thansulphur due to compact size of oxygen atom(inter-electronic repulsion is more in O). From sulphuronwards, enthalpy again becomes less negative upto Po.

20. Properties of oxygen are different from other elementsof the group due to its small size, high electronegativityand absence of d-orbital. Due to small size and high


15. Copper and zinc are refined by electrolytic method where impure metal is made to act as anode and a strip of puremetal acts as cathode. Here, the salt solution of the metal to be extracted is generally used as electrolyte.

16. At lower temperature, CO is a better reducing agent than C but at higher temperature (983 K or above), C is thebetter reducing agent.

17. Bauxite (Al O 2H O2 3 2 ) is an important ore of aluminium, haematite (F O2 3 ) and magnetic (Fe O3 4) are the important

ores of iron. Copper pyrites (CuFeS 2) is an important ore of copper.

18. Copper is extracted from low grade ores by leaching through acid or bacteria or by treating the ore with scrap Feor H2.


9/21

9

electronegativity, H O2 forms intermolecularhydrogen bonding which is not formed byH S2 .

Due to absence of d-orbital oxygen showscovalency of 4 and in practice rarely exceeds to itwhile other members of the group can exceedstheir covalence beyond four. Oxygen atom canform (p- p) bond due to small size.

21. Reducing property and acidic strengthincrease from H O2 to H Te2 due to decrease inbond dissociation enthalpy. However, theirthermal stability decreases fromH O to H Te2 2 .

22. Ozone is thermodynamically less stable thanoxygen because its decomposition into oxygenresults in the liberation of heat (H is negative)and increase in entropy ( S is positive). Thesetwo effects result in large negative Gibbs energy

change( )G for its conversion into oxygen.23. Ozone oxidises iodide ions to iodine and lead

sulphide to lead sulphate.

2I ( ) H O( ) O ( ) 2OH ( )2 3 + + aq l g aq

+ +I ( ) O ( )2 2s g

PbS( ) 4O ( ) PbSO ( ) 4O ( )3 4 2s g s g+ +

24. In quantitative method for estimating O3 gas,

ozone is treated with an excess of KI solutionbuffered with a borate buffer(pH 9.2)= . Iodine isliberated which can be t itrated against astandard solution of sodium thiosulphate.

25. TheS8 ring in both the monoclinicand rhombic

form is puckered and has a crown shape.

26. H O2 undergoes extensive H-bonding due to highelectronegativity of O-atom and hence, exists asa liquid. On the other hand, H S2 does notundergo H-bonding and hence, exists as adiscrete molecule and as a gas.

27. Moist sulphur dioxide behaves as a reducingagent.

It converts Fe ions to Fe ions3 2++ . It alsodecolourises acidified potassium permanganatesolution (a confirmative test forSO2 gas).

SO2 molecule is angular and is a resonancehybrid of the following two structures.

The twoS O bonds are equal.

28. Peroxomonosulphuric acid (H SO )2 5 and

peroxodi- sulphuric acid or Marshalls acid

(H S O )2 2 8 contain peroxide linkages in theirstructure.

29. Sulphuric acid, the king of chemicals or oil of vitriol, ismanufactured by contact process, reactions involved inwhich are

S O SO2 2+

2SO ( ) O ( ) 2SO ( )2 22 5

3

V Og g g+ ; veH =

SO H SO H S O 2H SO3 2 4 2 2 72

2 4Oleum

H O+

30. In SF6, S is sterically protected by six F atoms. Which, do

not allow H O2 molecules to attack at S atoms. As a resultof this, SF6 does not undergo hydrolysis.

31. Fluorine has smaller bond dissociation enthalpy thanchlorine while X X bond dissociation enthalpies fromCl onwords show the expected trendCl Cl >Br Br > I I due to small size and large

electron-electron repulsion among the lone pairs offluorine.

32. Ionisation enthalpy, electronegativity, bond dissociationenthalpy and electrode potential are higher for fluorinethan expected from other halogens whereas ionic andcovalent radii, melting and boiling points and electrongain enthalpy are quite lower than expected.

This is due to the small size, highest electronegativity,low F F bond dissociation enthalpy and non-availabilityof d-orbital.

33. Chlorine can be prepared by heating manganesedioxide with conc. HCl.

MnO 4HCl MnCl2 2+ + +Cl 2H O2 2

34. Chlorine reacts with sodium hydroxide solution in thefollowing manner.

(i) 2NaOH Cl NaCl NaOCl H O(Cold, dilute) Sodiu

2 2+ + +m hypochlorite

(ii) 6NaOH 3Cl 5NaCl NaClO 3H2 3 2( Hot,conc) Sodium ch

+ + +lorate

O

35. Chlorine water on standing loses its yellow colour dueto the formation of HCl and HOCl.

Cl H O HCl HOCl2 2+ +

HOCl HCl ONascent

+

Nascent oxygen formed by HOCl is responsible foroxidising and bleaching properties of chlorine.

36. Two different halogens may react to form interhalogencompounds of the type XX, XX3

, XX5, XX7 where X =high molecular mass halogen and X is smaller halogen.Their geometry is respectively linear, bent T-shaped,square pyramidal and pentagonal bipyramidal.

37. In all interhalogen compounds, X X bond is weaker thanX X or X X bond. So, these compounds are morereactive than individual halogens.

38. Fluorine reacts with water to produce oxygen andozone.

2F 2H O 4HF O2 2 2+ +

3F 3H O 6HF + O2 2 3+

39. The first compound of Xe was Xe PtF6+

which wasdiscovered by Neil Bartlett.


S

S S

S S

S

S

S

107

204pm

The structure of S8 ring inrhombic sulphur

OOS

OOS


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10

The d-andf-Block Elements1. Elements having partially filled d-orbitals in any of

their states are called d-block elements. These arealso called transition elements because theirproperties are intermediate of s and p-block

elements.

2. Zn, Cd, Hg of group 12 have full d 10 configurationin their ground state as well as in their commonoxidation states thus they are not regarded astransition metals.

3. The transition metals have high enthalpy ofatomisation. It first increases, reaches to themaximum in the middle of each series and thendecreases. It can be explained on the basis ofstrong inter atomic interaction due to unpairedelectrons. Greater is the number of unpairedelectrons, stronger is the resultant bonding.

4. Metals of second ( )4d and third ( )5d series have

high enthalpy of atomisation than thecorresponding elements of 3d series because ofstronger metal-metal bond. This is an importantfactor in accounting for the occurrence of muchmore frequent metal-metal bonding in compoundsof the heavy transition metals.

5. Ionisation enthalpy increases from left to right in aseries, but irregularities are observed due toirregular trends in electronic configuration. Firstfour members show little difference in values andlast four are also fairly close. Zn shows quite highvalue due to extra stability of completely filledorbital.

6. There is a fall in IE2

from Cr to Mn and from Cu toZn because after the removal of first electron, Cr,and Cu acquire a stable configuration i.e.,d d5 and 10. The high values of IE3 for Cu, Ni andZn explain why they show a maximum oxidationstate of +2.

7. Cu+ is unstable in aqueous solution and undergodisproportionation.

2Cu Cu Cu.; Cu2 2+ + + + is more stable thanCu+ due to much more H(hydration) of Cu2+ (aq)than Cu+ . This is more than that compensates forhigh IE 2 of Cu.

8. The values of E across the series are lessnegative because of general increase in the sum

of the first and second ionisation enthalpy. E

forMn and Zn are more negative because of half-filledand fully filled orbitals. E for Ni is more negativedue to the highest negative hyd H.

9. E

value for any metal depends on three factors;hydration enthalpy, ionisation enthalpy, enthalpy ofatomisation. Copper has high value of enthalpy ofatomisation and low value of hydration enthalpy and

also the high energy to transform Cu(s) to Cu ( )2+ aq isnot balanced by its hydration enthalpy, therefore it haspositive E.

10. Transition elements exhibit colour due tod- d transition, structure defects and charge transfer.Electrons of lower energy level of d -orbital absorbenergy from visible region for excitation to higher level.

11. Many transition metals and their compounds are usedas catalyst because of their ability to adopt multipleoxidation states and to form complexes.

12. Acidic strength of oxides of transition elementsincreases with increase inoxidation state of theelement e g. ., MnO (Mn )2+ is basic whereas

Mn O (Mn )2 77+

is acidic in nature.13. Both oxygen and fluorine being highly electronegative

can increase the oxidation state of a particulartransition metal. In certain oxides, the element oxygenis involved in multiple bonding with the metal and thisis responsible for the higher oxidation state of themetal.

14. The compounds in which small atoms like H, C, N etc.,occupy interstitial sites in the crystal lattice are calledinterstitial compounds.

These compounds are well known for transition metalsbecause small atoms can easily occupy the positionsin the voids present in the crystal lattices of transitionmetals.

15. Potassium dichromate is obtained from chromite oreas

4FeCr O + 8Na CO + 7O 2Fe O2 4 2 3 2 2 3

8 Na CrO 8CO2 4 2Sodiumchromate

+ +

2Na CrO +2H Na Cr O 2Na H2 4 2 2 7Sodiumdichromate

+ + + + 2O

Na Cr O 2KCl K Cr O 2NaC2 2 7 2 2 7Potassiumdichromate

+ + l

16. Potassium dichromate is used as primary standard

solution in volumetric analysis. In acidic medium,Cr O + 14 H + 6 2Cr + 7H O2 7

2 + 3+2

e

(E = 1.33 V)


40. Xenon fluorides are readily hydrolysed even by traces of water.

2XeF ( ) 2H O ( ) 2Xe ( )2 2s l g+ + +4HF ( ) O ( )2aq g

XeF H O XeOF 2HF6 2 4+ +

XeF 2H O XeO F 4HF6 2 2 2+ +XeF 3H O XeO 6HF6 2 3+ +

41. Heliumis also used in gas-cooled nuclear reactors and as diluent for oxygen in modern diving apparatus because ofits very low solubility in blood.

42. The geometry of XeF2, XeF4, XeOF4 and XeO3 are respectively linear, square planar, distorted octahedral, and

pyramidal.


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11

Thus, acidified potassium dichromate oxidises

iodides to iodine, sulphides to sulphur, iron (II) salts

to iron (III) and tin (II) to tin (IV).

Effect of pH on Cr O2 72

Cr O CrO2 72

42

H

OH

+

17. When pyrolusite ore is fused with alkali in the

presence of air or an oxidising agent like KNO3,

potassium permanganate is formed.

2MnO + 4KOH + O 2K MnO 22 2 2 4Potassiummanganate

+ H O2

3K MnO 4H2 4++ 2 KMnO + MnO + 2H O4 2 2

Potassiumpermanganate

MnO42 Electrolytic oxidation

in alkaline

solution Permanganate ion

MnO4

18. In acidic medium, KMnO 4 oxidises Fe to Fe ,2 3+ + SO3

to SO4, I to I2

whereas in neutral medium, itconverts I to IO3

and S O2 32 to SO4

2.

19. Due to the poor shielding effect of 4f electrons,effective nuclear charge increases and radiusdecreases from lanthanum to lutetium. Ionic radiidecrease in regular pattern but atomic radii follow

irregular pattern because configuration is irregular.The gradual and steady decrease in radii across the

period is known as lanthanoid contraction.

20. Due to lanthanoid contraction, the basic character ofoxides and hydroxides decreases from La (OH)3 toLu (OH)3 and Zr / Hf; Nb/Ta and Mo/ W are almostidentical in size.

21. Mischmetalis an alloy of rare earth elements (94%),iron (5%) and traces of C, S, Ca etc. It is used inmaking bullets, shells and lighter flint. Pyrophoricalloys contain Ce (40.5%), La + neodymium (44%)

Al, Ca and S.

22. Actinoids ions are generally coloured due tof-f transition. It depends upon the number ofelectrons in5 f-orbitals.

23. The decrease in atomic (or ionic) radii in actinoidelements (actinoid contraction) is greater than

lanthanoid contraction because 5f-electrons havepoor shielding effect as compared to 4f-electrons.Therefore, the effect of increased nuclear chargeleading to contraction in size is more in case ofactinoid elements.

24. Actinoids exhibit more number of oxidation statesthan lanthanoids. This is due to the fact that 5f, 6dand 7s levels are of comparable energies.


Coordination Compounds1. Double salts are the addition compounds that lose their

identity in solution. They exist only in solid state and haveproperties same as those of constituent compounds.

2. Coordination compounds or complexes dontcompletely lose their identity in solution. They exist insolid state as well as in solution. Their properties aredifferent from their constituents.

3. According to Werners theory, primary valency isionisable (i.e., species present outside the coordinationsphere is ionisable] whereas secondary valencies arenot.

4. Molecules or ions which donate a lone pair of electronsto the central atom or ion are calledligands. The number

of donor sites present in a ligand is called their denticity.e.g., en (ethylene diamine) is a bidentate ligand andEDTA is a hexadentate ligand.

5. When a ligand can ligate through two different atoms, itis called ambidentate ligand.

e g. ., NO , SCN , ONO2 .

6. The total number of ligands to which the metal is directlyattached is called coordination number(CN).

e.g.,[Co(NH ) ]3 63+, CN =6

[Co(en) ]33+ , CN= =3 2 6 (Qen is bidentate)

7. General formula for naming a neutral or cationic

complexis

ligand number ligand name meAlphabetically

+ +1 244 344 tal name

+(oxidation state of metal) + name of theligand outside the sphere.

8. General formula for naming anionic complexis

counter ion name+Present outsidethe sphere

1 2444 3444 ligand number

+ ligand name

Inside the sphereand alphabetically

1 244 344+ metal name

+ ate + (oxidation state of metal)

9. Compounds having the same molecular formula

but different arrangement of atoms are called

isomers and this phenomenon is cal led

isomerism.

10. (i)Complexes exhibit linkage isomerism when have

ambidentate ligand like NO2, SCN etc.

(ii)Complexes exhibit coordination isomerismwhen cationic and anionic entities are complexes

of two different metals.

(iii) Hydration isomerismarises due to difference in

the number water molecules inside and outsidethe coordination sphere.

(iv) Ionisation isomerism arises due to difference in

ligand or counter ion.

11. Geometrical isomerismis shown by complexes of

the type [MA B ],2 2 [MABXL], [MA B ]3 3 , [MA XY]2 ,

[MA X ]4 2 , [M(AA) X ]2 2 where M = metal, A,B,X,L,Y

are unidentate ligand and A A =

bidentate ligand.Here, if same group occupies adjacent positions,

the isomer is called cis and if the same group

occupies opposite sides, the isomer is calledtrans.


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12

12. Tetrahedral complex do not show geome-trical isomerism because the relative positionsof unidentate ligands attached with centralmetal atom are the same with respect to each

other.

13. Optical isomerism is shown by thecompounds having lack of plane of symmetry.Complexes of the type [M(AA) ]3 , [M(AA) X ]2 2 ,[M(AA)X Y ]2 2 exhibit optical isomerism.

where, M = metal, X ,Y= unidentate ligandand A A =bidentate ligand.

14. From VBT, the hybridisation and geometry of acomplexes is find as

(i)Find the oxidation state of central atom andwrite the electronic configuration of the metalion.

(ii)Pair up thed-electrons, if ligands are CO, CN

NH3etc (strong field ligand).

(iii)Now find whether unpaired electrons arepresent or not. If present, the complex isparamagnetic and if not, it is diamagnetic.

(iv)Find hybridisation and shape from the orbitalsoccupied by ligand. e.g., If there are 4 ligand(unidentate), hybridisation may be sp3

(tetrahedral geometry) ordsp2 (square planargeometry). If there are 6 ligands, hybridisationmay bed sp2 3 orsp d3 2 (octahedral geometry).

(v)If unpaired electrons are present the complexis coloured due tod-d transition but the colour

of KMnO4is due to charge transfer.

15. According to CFT, degenerate d-orbitals in the presenceof ligand split up into two sets of energyviz eg and t2g set.

16. The difference of energy between the two sets of

degenerate orbitals as a result of crystal field splitting isknown asCrystal Field Stabilisation Energy(CFSE). It isdenoted by o .

17. Ligands can be arranged in a series in the order ofincreasing field strength. This series is known asspectrochemical series.

l Br SCN Cl F OH C O2 42 < < < < < <

< < < < < < P, it becomes more energetically favo- urable for

the fourth electron to occupy a t g2 orbital withconfiguration t eg g2

4 0 . Ligands which produce this effectare known as strong field ligands and form low spincomplexes.

19. cis-platin [PtCl (NH ) ]2 3 2 is used for the treatment of cancer.

EDTA complex of Ca is used for treating lead poisoning.

20. Metal carbonyls are the compounds in which CO(corbon monoxide) present as a ligand. The MC bond is formed by the donation of lone pair of electrons ofcarbonyl carbon to vacant orbital of metal whereas the MC bond is formed by the donation of a d-electron pairof metal into the vacant antibonding * orbital of CO.

Haloalkanes andHaloarenes1. Haloalkanes and haloarenes are obtained by

the replacement of a hydrogen atom of analkane and arene respectively by a halogenatom(F, Cl, Br, I).

2. Haloalkanes are named as X-haloalkaneswhere, X represents the position of halogen

atom.

e.g., CH CH CH I3 2 2 (1-iodopropane).

3. Haloalkanes are obtained from alcohols bytreating them with HX ( anhy ZnCl )2+ ,PCl , PCl , SOCl5 3 2 etc.

R RX

OH H (anhy ZnCl )

PCl , PCl , SOCl

2

5 3 2

Cl

SOCl2 is the best reagent as the by productsare gases.

4. Haloalkanes are also prepared by the action ofhalogen acid (HX) on alkene. The reactionfollows Markownikoffs rule, i.e., the negativepart of the reagent goes to the carbon bearingless number of hydrogen atoms.

5. Fluoroalkanes are prepared by treating alkylchloride/bromide in the presence of a metallic

fluoride such as AgF,Hg F2 2,CoF2 orSbF3. This reaction isknown as Swarts reaction.

CH Br AgF CH3Methyl

bromide

Silver fluoride

+ 3F+ AgBrFluoromethane

6. Generally bromoalkanes are prepared by the reactionknown as Borodine Hunsdiecker reaction.

CH COOAg Br CH Br CO AgBr3 2 3 2CCl4+ + +

7. With increase in the size of halogen atom,carbon-halogen bond length increases and hence,reactivity increases. Thus, RI is most reactive towardsS 1N and S 2N reactions.

8. From F to I, the electronegativity of halogen decreases,therefore the polarity of theCXbond and thus, dipolemoment decreases accordingly. However fluorides havelower dipole moment than chlorides because of very smallsize of F.

CH Cl CH F CH Br CH I3 3 3 3> > >

9. Alkyl halides are slightly soluble in water, because they donot form H-bonds with water.

10. Due to better symmetry of para isomers as compared to

ortho and meta isomers, para isomers have high meltingpoints as compared to their ortho and meta isomers.



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13

11. S 1N mechanism involves carbocation intermediate, thus

the reactant giving more stable carbocation, is morereactive towardsS 1N reactions. The order of reactivity ofalkyl halides towards these reactions is

3>2>1

These reactions result in racemisation i.e., retention aswell as inversion.

12. S 2N mechanism involves transition state, thus less

hindered alkyl halides readily undergo these reactions.These reactions result in inversion of configuration.

13. In the presence of polar solvent, KCN readily ionises tofurnish CN ions. As CC bond is more stable thanC N bond, so cyanide is predominantly formed.

R R + + Br CN CN Br

However, AgCN does not ionise so attacks through Nand results in the formation of isocyanide.

R RBr AgCN NC AgBr + +14. Reaction of KNO3 with RBr results in the formation of

RONO2 (nitrite) whereas reaction of RBr with AgNO3results in RNO3 (nitrate) predominantly.

15. An object or molecule which is non-superimposable onits mirror image is calledchiraland this property is calledchirality.

16. Achiralor asymmetric carbonis that carbon all the fourvalencies of which are satisfied by four different groups.Such a carbon bearing molecule is generally opticallyactive.

17. An equimolar mixture of two enantiomers (d and l -forms)is called racemic mixture. It is represented as dl or

forms and will be optically inactive. The process ofconverting d or l-form of an optically active compoundinto racemic form ( )dl is called racemisation.

18. Grignard reagents are highly reactive and react withwater (a good source of proton) to give hydrocarbons.

R X R X Mg + H O H + Mg(OH)2

Hence, traces of moisture must be avoided during theuse of a Grignard reagent.

19. Cl, Br etc are ortho/para directing groups and direct theincoming group in electrophilic substitution reactions atortho and para positions.

20. Towards nucleophilic substitution reactionshaloarenes are less reactive than haloalkanesdue to resonance effect (double bond characterin C Cl bond), sp2 hydridisation of C bearing

halogen atom and instability of phenyl cation.

21. When aryl halide is heated with alkyl halide in thepresence of sodium in dry ether, halogen atomis replaced by alkyl group and alkylarene isformed. This is called Wurtz-Fittig reaction.

22. When haloarenes react with sodium in thepresence of dry ether, two aryl groups are joinedtogether and diphenyl is formed. This reaction iscalled Fittig reaction.

23. In the presence of sunlight, chloroform is slowly

oxidised by air to produce a highly poisonousgas, carbonyl chloride or phosgene, COCl2.Thats why it is stored in dark coloured bottlesfilled up to brim.

24. Chlorofluorocarbon compounds of methaneand ethane are collectively known as freons.

In stratosphere, freon is able to initiate chainreactions that can result in depletion of ozonelayer. Since, freon has been found to be one ofthe factors responsible for the depletion ofozone layer, they are being replaced by otherharmless compounds in many countries.

Alcohols, Phenols andEthers1. Alcohols and phenols are formed when a hydrogen atom

in a hydrocarbon, aliphatic and aromatic respectively isreplaced by OH group. Alcohols are named byreplacing e of parent alkane with suffix ol.

2. Alcohols are prepared by hydration of alkene or reactionof Grignard reagent with aldehydes or ketones.

HCHO gives 1 alcohol, RCHO give 2 alcohol andketone give 3 alcohol with Grignard reagent.

3. Chlorobenzene on fusion with NaOH at 623 K and320 atm pressure gives sodium phenoxide which on

acidification yield phenol.


Cl + 2Na + ClCH3Dry-

Toluene

ether

CH +2NaCl3

ChlorobenzeneMethyl Cloride

Cl + 2Na + Cl Dry-

Diphenyl

ether

+ 2NaCl

ONa+ OH

623 K

300 atm

Phenol

Cl

+NaOH

HCl

Sodium phenoxide

Chlorobenzene


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14


4. Cumene (isopropyl benzene) on aerial oxidationform cumene hydroperoxide which uponsubsequent hydrolysis with dilute acid givesphenol and propanone.

5. The boiling points of alcohols and phenolsincrease with increase in number of C-atoms(increase in van der Waals forces). Amongstisomeric alcohols, the boiling points decreaseswith increase in branching in the carbon chainbecause of decrease in van der Waals forceswith decrease in surface area.

6. Phenols are more acidic than alcohols, dueto more stabilisation of phenoxide ion formedby delocalisation of negative charge. Presence

of electron withdrawing groups such as NO , CHO2 , etc increases the acidicstrength of phenol by stabilising phenoxide ionwhereas electron releasing group like CH3reduces the acidic strength of phenol.

7. Alcohols undergo dehydration when treatedwith conc.H SO2 4 orH PO3 4.

The steps involved in this process is

Step I Protonation of alcohol

CH CH O H H CH CH O|H

H3 2 3 2Fast

Protonated alc

+ + +

ohol

Step II Formation of carbocation (ratedetermining step)

CH CH 2 O

H

H CH CH H O3 2 3 2 2

++ +

Step III Elimination of proton

CH CH CH CH H3 2 2 2Ethene

+ +== +

8. Esterification is the reaction of formation ofester when alcohol or phenol react with acids ortheir derivatives.

9. OHis anortho/paradirecting activating group

in aromatic electrophilic substitution reactions.

10. Phenol gives 2,4,6-trinitrophenol (or picric acid) whentreated with conc. HNO3and 2, 4, 6-tribromophenol whentreated withBr H O2 2/ . However, when phenol is treatedwith Br

2in CS

2, it gives o and p-bromophenol.

11. On treating phenol with CHCl3 (chloroform) in the

presence of sodium hydroxide, aCHO group isintroduced atorthoposition of benzene ring. This reactionis called Reimer-Tiemann reaction. In this reaction,electrophile is dichlorocarbene ( CCl2

).

12. Phenol is converted to benzene on heating with zinc dust.

13. Alcohols are made unfit for drinking by mixing somecopper sulphate (CuSO )4 and pyridine in it. This processis known as denaturation of alcohol.

14. Ethers are named as alkoxyalkane where alkoxy isgenerally the smaller group attached with O. Ethanol isdehydrated to ethoxyethane at 413 K in the presence ofsulphuric acid.

2C H OH2 52 4

Ethanol(excess)

Conc. H SO

413 K C H O C H H O2 5 2 5 2

Ethoxyethane +

Step I Protonation of alcohol.

CH CH O H H3 2

Fast +

+ CH CH O

H

H3 2

+

Step II Nucleophilic attack by unprotonated alcoholmolecule on protonated alcohol molecule.

CH CH O

H

CH CH OH

H3 2 3 2

+

+

CH CH O

H

CH CH H O3 2 2 3 2

++

Step III Loss of proton to form ethoxy ethane

CH CH O

H

CH CH3 2 2 3

+

CH CH O CH CH +H3 2 2 3Ethoxy ethane

+

OH

O2

CH CH3

H+

Cumene

3

CH COOH3

CH3

H O2

Phenol

+ CH COCH3 3

Acetone

(propanone)

Cumenehydroperoxide

ONa OH

CHCl3

aq.NaOH

NaOH

H+

a

CHCl2

Intermediate

Salicylaldehyde

CHO CHO

+

Benzene

+ Zn + ZnO


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15


15. In Williamsons synthesis, a primary alkyl halideis allowed to react with sodium alkoxide.

R X R R +

+

Alkylhalide

Sodiumalkoxide

O Na O +R X

Ether

Na

In case of secondary or tertiary halides,elimination product is the major product.

16. The cleavage of C O bond in ethers takesplace under drastic conditions with excess ofHX.

R R X R RX + +O H OHAlkylhalide

Ether Alcohol

K373

R X R X + +OH H H O2

Alkyl aryl ethers are cleaved at alkyl-oxygen bond due tothe more stable aryl oxygen bond. The reaction givesphenol and alkyl halide.

17. Alkoxy group( )OR activates the aromatic ring towardselectrophilic substitution and directs the incomingelectrophile ato-and p-positions (because of the negativecharges at o- and p-positions which indicates the moreelectron density at these positions).

18. Anisole undergoes Friedel Crafts reaction, i.e., the alkylhalide and acyl groups are introduced at o-andp-positions by reaction with alkyl halide and acyl halide inthe presence of anhydrous aluminium chloride (a Lewis

acid) as catalyst.

Aldehydes, Ketones andCarboxylic Acids1. The C O== group is known as the carbonyl group

and the compounds containing C O== group areknown as carbonyl compounds.

In aldehydes, the carbonyl group is bonded witha carbon and a hydrogen while in ketones, it isbonded with two carbon atoms. Aldehydes arenamed by adding suffix al and ketones byadding suffix one.

2. Aldehydes and ketones are obtained by theoxidation of 1 and 2 alcohols respectively byPCC (Pyridine Chloro Chromate) orK Cr O / H SO2 2 7 2 4.

+CH OH CHO H O2 2[O]

3. Aldehydes are obtained by the reduction ofcarbonyl chloride with Pd BaSO/ ,4 S(Rosenmund reduction).

R RC H CHOPd BaSO S

HOCl + 2

4

2

/ ,

or by the reduction of CN with SnCl HCl2+(Stephen reduction)

R RCN H CHO23

2

H O

SnCl HCl+

+

+

4. Etard reaction is also used to synthesisbenzaldehyde from toluene by treating it withCrO Cl CS2 2 2/ followed by hydrolysis.

C H CH CrO Cl C H CHO6 5 3 2 23

26 5

H O

CS

Benzaldehyde

+ +

5. Boiling points of aldehydes and ketones arehigher than hydrocarbons and ethers ofcomparable molecular masses. This is becauseweak intermolecular association arises inaldehydes and ketones due to dipole-dipoleinteractions.

6. Theorder of reactivityof aldehydesand ketonesis

HCHO> CH CHO> C H CHO > CH COCH3 6 5 3 3

> C H COCH6 5 3

7. Carbonyl compound formcyanohydrinwhen treated withHCN in the presence of a base.

C O HCN C OH

CN== + (cyanohydrin)

8. Aldehydes form hemiacetaland acetalwhen treated withone or two equivalents of alcohol respectively in thepresence of dry HCl gas.R

R

R R

H C O OH

HCl

Hemiacetal

== +

H C O

OH

H O

OH, HCl

2

Acetal

R R R

RH C

O

O

Ketones in this reaction form ketals.

9. Carbonyl compounds form 2,4-DNP derivatives (orangeor yellow or red ppt) with 2,4-DNP (2,4-dinitrophenylhydrazine), Brady's reagent.

10. Aldehydes reduce Tollens reagent (ammonical silvernitrate ) into silver mirror, Fehlings solution into red ppt ofCu O2 and Benedicts solution into red ppt. These

reactions are not given by ketones.11. C O== group is reduced to CH2 group by

ZnHg/conc. HCl (Clemmenson reduction) or byNH NH KOH2 2 + (Wolff-Kishner reduction).

12. Aldehydes and ketones containing-H atoms undergoaldol condensation in the presence of dilute alkali ascatalyst e.g.,

-hydroxy aldehydes or ketones are collectivelly calledaldols and the reaction is called aldol condensation.

OHO R

+H X +R X

2CH CHO3Ethanal

Dil. NaOHCH CHCH CHO3 2

H O2

DCH CH

3 CH

CHOBut-2-enal(aldol condensation product)

OH3-hydroxybutanal (aldol)


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16


13. When aldehydes having lack of-H atoms are treatedwith conc. alkali, it disproportionates to give reductionproduct alcohol and oxidised product salt of acid.

This reaction is calledCannizzaro reaction.

2H CHO conc.KOH H CH OH2Methanol

+ + H COOKPotassiumformate

14. Although semicarbazide has two NH2 groups butone which is directly attached to C O== is involved inthe resonance. Consequently, electron density on thisNH2 group decreases and hence, it does not act asa nucleophile. On the other hand, the lone pair ofelectrons on the other NH2 group is not involved inresonance and hence, is available for nucleophilicattack on the C O== group of aldehydes and ketones.

15. Due to+ Reffect of benzene ring, the electron densityin the carbonyl group of benzaldehyde increases. Thisin turn, increases the electron density in the C Hbond of aldehyde group. As a result, the C H bondbecomes stronger and hence, only oxidising agent like

Tollens agent; Ag (NH )3 2+ ( 0.8 V)

Ag / Ag+E = can

oxidise C H to C OH to form carboxylic acids butweaker oxidising agent like Fehlings solution or

Benedicts solution ( 0.18 V)Cu / Cu2+ +

E = fail to oxidise

benzaldehyde to benzoic acid.

16. Carbon compounds containing a carboxyl functionalgroup (COOH) are known as carboxylic acids.Their names are derived by replacing the terminal efrom the name of corresponding straight chain

alkane by suffix oic acid.

17. Nitriles are first hydrolysed to amides and then toacids in the presence of H or O+

H as catalyst. Mild

reaction conditions are used to stop the reaction atthe amide stage.

R R

CN C||O

NHH O

H+

or OH

2

2

H+

or OHCOOHR

18. Aromatic acids are obtained by vigorous oxidation ofalkyl benzene with chromic acid or acidic or alkalineKMnO4.

19. As compare to hydrocarbons, aldehydes andketones, carboxylic acids have higher boilingpoints because they have high extent of hydrogenbonding with water, due to which they exist as

associated molecules.

20. Melting point of an acid containing even number ofcarbon atoms is higher than the adjacent memberscontaining odd number of carbon atoms.

21. Carboxylic acids are stronger acids than phenols

because carboxylate ion is much more resonancestabilised than phenoxide ion. Electron withdrawinggroups (EWG) increase the stability of thecarboxylate ion by dispersing the negative chargewhile electron donating group decrease thestability of the carboxylate ion by intensifying thenegative charge.

22. Carboxylic acids having an -hydrogen arehalogenated at the -position on treatment withchlorine or bromine in the presence of small amountof red phosphorus to give -halocarboxylic acids.The reaction is known as Hell-Volhard-Zelinskyreaction.

R CH COOH22(ii) H O

(i) /Red phosphorusX2

R

X

CH|

COOH

-halocarboxylic acidwhere, X= Cl Br,

23. Aromatic carboxylic acids undergo electrophilicsubstitution reactions in which the carboxyl groupacts as a deactivating and meta-directing group.

However, they do not undergo Friedel-Craftsreaction because the carboxyl group isdeactivating and the catalyst aluminium chloride(Lewis acid) gets bonded to the carboxyl group.

Amines1. Amines are derivatives of ammonia, obtained by

replacement of one, two or three hydrogen atoms byalkyl/aryl groups.e g. .,

2. In IUPAC system, amines are named asalkanamines,derived by replacement of e of alkane by wordamine.

3. Both aliphatic and aromatic primary amines can beprepared by the reduction of nitro compounds eithercatalytically with H2 in the presence of Raney Ni, Pt or

Pd or chemically with active metal in acidicmedium.

C H NO 3H6 5 2 2Nitrobenzene

Sn HCl

or Fe H+ +

+ Cl AnilineC H NH H O6 5 2 2+

4. In Hofmann bromamide reaction, amides ontreatment with Br2/NaOH gives an amine havingone carbon less than the parent amide.

R

+ + C

O

NH Br 4NaOH2 2

R + + +NH Na CO 2NaBr 2 H O2 2 3 2

CH3

KMnO /KOH4

H O3+

HeatCOOH

3 amine

3NCH NH , CH NH CH ,CH 3 2 3 3 3

CH31 amine 2 amine


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17

5. In Gabriel phthalimide synthesisa phthalimide istreated with ethanolic KOH and forms potassium salt ofphthalimide which on heating with alkyl halide followedby alkaline hydrolysis forms corresponding primaryamines.

This method produces only primary amines, without the

traces of secondary or tertiary amines. So, this methodis prefered for the synthesis of primary amines.

6. 1 amines have two, 2 amines have one while3 amines have no hydrogen linked to nitrogen.Therefore, the order of boiling point of amines is

1amines> 2 amines> 3 amines7. Aliphatic amines are stronger bases than ammonia due

to +I effect (electron donating power) of alkyl groups,due to which electron density on nitrogen atomincreases and hence, they can easily donate theirelectrons as compared to ammonia.

Aromatic amines are weaker bases than ammonia dueto electron withdrawing nature of aryl group.

8. Larger the value of Kb or smaller the value of p bK ,

stronger is the base.

9. Order of basicity of amines in gaseous phase followsthe expected order.Tertiary amine > Secondary amine

> Primary amine

> Ammonia

10. If we combine the effect of + I group, steric effect and

solvation effect and if the alkyl group is small, i e. . C H3,

then there is no steric hindrance to H-bonding andhence H-bonding predominates over + Ieffect. Since,all these effects are favourables for 2amine, therefore,

order of basicity is2amine> 1 amine> 3 amineIf the alkyl group is bigger than CH 3 group, there is

steric hindrance to H-bonding and hence + I effectpredominates over H-bonding. Therefore, the order is

2 amine> 3 amine > 1 amine11. In anilinium ion there is only two resonating structures,

therefore, it is less stable than aniline (five resonatingstructures).

12. In case of substituted aniline, electron releasinggroups like CH3, OCH3, NH2 increasebasic strength and electron withdrawing groupslike NO2, X,COOH decrease basicstrength.

13. Primary amines on heating with chloroform andethanolic potassium hydroxide form isocyanidesor carbylamines which have foul smell. Thisreaction is called carbylamine reaction orisocyanide test. This reaction is used to testprimary amines.

e.g., R + +

NH CHCl 3KOH2 31 amine Chloroform

R +NC + 3KCl 3H Osocyanide

2I

14. Primary aliphatic amines when treated with HNO 2(NaNO2 +HCl) gives alcohol whereas primary

aromatic amines in this reaction give diazoniumsalt (C H N Cl )6 5 2

+ .

15. In aniline electron density at ortho- and para-positions to the NH2 is high. Therefore, NH2group is ortho or para directing and powerfulactivating. To control its activity aniline is subjectedto acetylation before subjecting to electrophilicsubstitution reactions.

16. Reactions involving displacement of nitrogen

(Sandmeyer reaction)

CuCl/HClC H Cl + N6 5 2

+(Gatterman reaction)

Cu/HBrC H Br + N6 5 2 CuX

+ +

HBF46 5 3 2C H F + BF N HX

++H PO H O3 2 2

6 6 2C H N + +H PO H3 3H O2

6 5 2C H OH + N H + X

17. Benzene diazonium chloride reacts with phenol inwhich phenol molecule at its para position iscoupled with diazonium salt to give the productp-hydroxyazobenzene, hence the reaction isknown as coupling reaction. The azo products

obtained are coloured and used as dyes.


N+

NCl

Benzenediazonium

chloride

CO

NH + KOH (alc.)

Phthalimide

H O2 CO

N K +

Potassium phthalimide

R X

CO

Na+

CONa + 1 amine

R NH2NaOH( )aq CO

CO

N-alkylphthalimide

NR

O

O

+

N+

NCl

+ H OH OH

N N OH+Cl +H O 2

p-hydroxyazobenzene(orange dye)


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18


Biomolecules1. Carbohydrates may be defined as optically active

polyhydroxy aldehydes or ketones or the compoundswhich produce such units on hydrolysis.

2. Simple carbohydrates which cannot be hydrolysed tosimpler carbohydrates are called monosaccharides.e g. .,glucose, fructose, ribose, etc.

3. Carbohydrates which give 2-10 monosaccharide units onhydrolysis are called oligosaccharides (e.g., maltose,lactose) and that give a large number of monosaccharideunits are called polysaccharides e g. ., starch, cellulose,etc.

4. Carbohydrates in which ketonic or aldehydic groups arefree and are capable of reducing Fehlings solution orTollens reagent are known as reducing sugars. e.g., allmonosaccharides and disaccharides except sucrose.

5. Carbohydrates in which aldehydic or ketonic group arebonded and those which do not reduce Fehling solutionor Tollens reagent are called non-reducing sugars.e.g.,sucrose.

6. On prolonged heating with HI, glucose gives n-hexanewhich suggest that all the six carbon atoms in glucose arelinked linearly.

HOCH (CHOH) CHO + HI2 4

CH (CH ) CH3 2 4 3-hexanen

7. When oxidised with bromine water, glucose gives gluconicacid and with HNO 3 it gives saccharic acid.

(CHOH)

CH OH

CH OH

(CHO4

2

2

2

Gluconic acid

Br water

H)

CH OH

CHO

(CHOH)

COOH

COO

4

2

3 4HNO

Saccharic acid

H

8. Acetylation of glucose with acetic anhydride givesglucose penta-acetate which confirms the presence offiveOHgroups. Since, it exists as a stable compound,fiveOH groups should be attached to different carbonatoms.

(CHOH)

CH OH

CHO

4

2

3

3

(Acetylation)

CH COOCH COO

O

(Acetic anhydride)( )

CH

CHO

O C

O

CH

CH O C

O

CH

3 4

2 3Glucose penta -acetate(stable compound)

9. Open chain structure of D-glucose could not explain thefollowing reactions

(i) Despite having the aldehyde group, glucose does notgive Schiffs test and 2,4-DNP test.

(ii) Glucose does not react with sodium hydrogensulphide to form addition product.

(iii) The penta-acetate of glucose does not react withhydroxyl amine showing the absence of freeCHO.

10. The two monosaccharides are joined together by an oxide

linkage formed by loss of a water molecule. Such alinkage is known as glycosidic linkage.

11. Mutarotationis the spontaneous change in thespecific rotation of an optically active compo-und towards an equilibrium value.

12. When two cyclic forms of a carbohydrate differin configuration of hydroxyl groups at C-1, theyare called anomers and represented as and-form.

13. The six membered cyclic structure of glucose isknown as pyranose structure( or).

14. Although, sucrose is dextrorotatory but afterhydrolysis it gives dextrorotatory glucose andlaevorotatory fructose (the mixture islaevorotatory because laevorotation is morethan dextrorotation). Since, hydrolysis ofsucrose brings about a change in the sign ofrotation i e. ., from dextro ( )+ to laevo ( ) hencethe product is known as invert sugar.

15. Maltose is composed of two-D-glucose unitsin which C-1 of one glucose unit (I) is linked toC-4 of another glucose unit (II).

16. Lactose is composed of -D-galactose and-D-glucose.

17. Starch consists of two components namelyamylose and amylopectin.

Amylose is soluble in water and constitutes15-20% of starch while amylopectin is insolublein water and constitutes about 80-85% ofstarch. In both amylose and amylopectin, theD-glucose units are linked through-glycosidiclinkages between C-1 of one glucose unit andC-4 of the next glucose unit whereas inamylopectin the branching occurs by C1-C6glycosidic linkage.

18. Amino acids which are synthesised by thebody are called non-essential. On the otherhand, those which cannot be synthesised in thehuman body and are supplied in the form ofdiet because they are required to proper healthand growth are called essential amino acids.

19. In-helix, polypeptide chain forms all possiblehydrogen bonds betweenNHgroup of each

amino acid and C O== of an adjacent turnleading to twisting of polypeptide chain into aright handed helix.

-D-(+)-glucopyranose

O

OH14

H5

3 2 OH

H

HO

H

6CH OH2

H

OHH

-D-(+)-glucopyranose

O

OH14

H5

3 2

OH

HHO

H

CH OH2

H

OHH

6


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19

20. In -structure or -pleated sheet all peptidechains are stretched out to maximum extensionand they laid side by side which are held together

by intermolecular hydrogen bonds.21. When there is a physical change like change in

temperature or chemical change like change in pHin the native form, the hydrogen bond getsdisturbed. As a result, globules unfold and helicesget uncoiled and protein loses its biologicalactivity. This is known as denaturation of protein.During denaturation 2 and 3 structures destroyedbut 1 structure remains intact.e.g.,coagulation ofegg white on boiling and curdling of milk.

22. Biological catalysts are known as enzymes theyare made up of proteins. Enzymes are veryspecific for a particular reaction and for a particularsubstrate. e.g., invertase, zymase, etc.

23. Amino acids within the same molecule contain anacidic (carboxyl) group and a basic (amino) group.

Carboxyl group in aqueous solution loses a protonwhile amino group accepts a proton results in theformation of Zwitter ion.

H N CH|

COOH H N CH|

COO2 3

Zwitter ion

+

R R

In Zwitter ionic form, -amino acids showamphoteric behaviour, as they react with acids andbases both.

24. Deficiency diseases of vitamin A, B 6, B12, C, D and E

are respectively xerophthalmia, convulsion, perniciousanaemia, scurvy, rickets and infertility.

25. Because vitamin B and C are soluble in water, they areexcreted readily in urine and hence, cannot be storedin the body.

26. Nucleic acids are of two types: deoxyribonucleic acid(DNA) and ribonucleic acid (RNA).

27. DNA is composed of deoxyribose sugar; adenine andguanine purine base; thymine and cytosine pyrimidinebase and phosphoric acid. Its structural unit is callednucleotide.

Nucleotide= phosphate+ sugar + baseNucleoside= sugar+ baseNucleotide= nucleoside+ phosphate.

28. James Watson and Francis Crickproposed a doublehelical structure of DNA.

29. The process by which a DNA molecule produces twoidentical molecules of itself in the nucleus of the cell iscalled replication.

30. RNA is composed of ribose sugar, adenine andguanine purine base; uracil and cytosine pyrimidinebase and phosphoric acid.

31. There are three types ofRNAs

(i) Ribosomal RNA ( r-RNA)

(ii) Messenger RNA ( m-RNA)

(iii) Transfer RNA (t-RNA).


Polymers1. Polymers can be defined as compounds of high

molecular mass (103- 10 u)7 formed by combination of

large number of small molecules. The smallmolecules which constitute the repeating units in apolymer are called monomer units.

2. Homopolymers are those addition polymers inwhich single monomeric species is involved in their

formation. e.g.,polythene.

nCH CH2 2Ethene==

(CH CH )2 2Polythene

n

3. Copolymers are those addition polymers in whichtwo different monomeric species are involved in theirformation. e.g.,Buna-S.

n nCH CH CH CH C H CH CH2 2 6 5 21, 3-butadiene Styr

== == + ==ene

(CH CH CH2Butadiene- styrenecopolymer(Buna -S)

== CH CH C H )

C H

2 2

6 5

n

4. Elastomers are rubber-like solids with elastic

properties. These polymers have the weakestintermolecular forces, which permit the polymer tobe stretched. A few cross-links are introduced inbetween the chains, through which the polymer

regain its original position after the force is releasedin vulcanised rubber. e.g., Buna-S, Buna-N,neoprene, etc.

== ( CH C

Cl

CH CH )

Neoprene

2 2 n

5. Fibres have strong intermolecular forces like

hydrogen bonding or dipole-dipole interactions. Theyare useful in making fibres as their molecules arelong and thread-like. They possess high tensilestrength, high modulus and less elasticity. Thesestrong forces also lead to close packing of chainsand imparts crystalline nature. e.g., nylon-6,6,(polyamides), terylene (polyester) etc.

6. Thermoplastic polymers are those polymers inwhich intermolecular forces are intermediatebetween those of elastomers and fibres. They arelinear or slightly branched long molecules which arecapable of repeatedly softening on heating andhardening on cooling. e.g.,polystyrene, polythene,PVC, etc.

(CH CH )|Cl

2 n (PVC)


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7. Thermosetting polymers are heavily cross-linked orbranched molecules, which on heating undergo extensivecross-linking and become infusible. Once they get set,they cannot be reshaped and reused. e.g., bakelite,urea-formaldehyde resins, etc.

8. Steps involved in free radical polymerisation are

Step I Chain initiation

(C H COO) (C H COO) 2C H6 5 2 6 52

6 5CO

Step II Chain propagation

C H CH CH C H CH C H6 5 2 2 6 5 2 2+ ==

Step III Chain terminating

2C H (CH CH ) CH CH6 5 2 2 2 2

n C H (CH CH ) CH CH CH6 5 2 2 2 2 2 n

(CH CH ) C H2 2 6 5 n9. Polymers and their monomers

(i) Polymer Polythene

Monomer Ethene(CH CH )2 2==(ii) Polymer Teflon

Monomer Tetrafluoroethylene. (CF CF )2 2==(iii) Polymer Orlon or acrilan, polyacrylonitrile (PNA)

Monomer Acrylonitrile [CH CH(CN)2 == ](iv) Polymer Terylene or dacron.

Monomers Ethylene glycol (CH OH CH OH2 2 ),

terephthalic acid,

(v) Polymer Nylon 6 or perlon

Monomer Caprolactam

(vi) Polymer Nylon 6,6

Monomers Adipic acid [HOOC(CH ) COOH]2 4 ,

hexamethylene diamine[H N(CH ) NH2 2 6 2 ](vii) Polymer Bakelite

Monomer Formaldehyde (HCHO),

phenol (C H OH)6 5

(viii) Polymer PMMA

Monomer Methyl methacrylate

(CH C

COOCH

CH )2

3

3==

(ix) Polymer Cellulose

Monomer -D-glucose.(x) Polymer Neoprene or synthetic rubber

Monomer Chloroprene

CH C

Cl

CH CH2 2==

==

(xi) Polymer Buna-S

Monomer Buta-1,3-diene

(CH CH CH CH )2 2== == ,styrene (C H CH CH )

6 5 2

==(xii) Polymer Buna-N

Monomer Buta-1,3-diene

(CH CH CH CH )2 2== == ,acrylonitrile (CH CH CN)2 ==

10. Natural rubber is cis polyisoprene, a polymerof isoprene (2-methylbuta-1, 3-diene).

11. Vulcanisation is the heating of natural rubberwith sulphur and an appropriate additive at atemperature range between 373 K to 415 K.Sulphur forms cross-links at the reactive sites ofthe double bond and thus, rubber gets stiffened

i.e., becomes less sticky and plastic, more

resistant to swelling by organic liquids and hasenhanced elasticity. Physical properties of rubbercan be improved by vulcanisation.

12. Rubber made with 1-3% sulphur is soft andstretchy and is used in making rubber bandsand rubber made with 5% sulphur is more rigidand is used in the manufacture of tyres forautomobiles etc. It is also used in makingfootwears, battery boxes, foam mattresses,balloons, toys, etc.

13. Main constituent of bubble gum isstyrene-butadiene copolymer.

14. Biodegradable polymers are those polymerswhich get decomposed by themselves over aperiod of time due to environmentaldegradation by bacteria.

e.g., PHBV(Poly -hydroxy butyrate-co--hydroxy valerate).

NC O

CH2

CH2H C2

H C2

H C2

(HOOC COOH)

Chemistry in Everyday Life1. Chemotherapy means treatment of a disease with the

help of chemicals in the form of medicines.

2. Drug target are the biomolecules such ascarbohydrates, lipids, proteins and nucleic acids withwhich drugs usually interact.

3. A drug travels through the human system in order toreach the target. So, the drug should be designed insuch a way that it reaches the target without beingmetabolised in between.

4. Competitive inhibitors compete with thenatural substrate for their attachment on theactive site of enzymes.

5. Some drugs, instead of binding to the enzymesactive site, bind to a different site of enzyme,

which is calledallosteric site. Due to this action,the shape of the active site is changed to theextent that substrate does not recognise it.


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6. The message between two neurons and that betweenneurons to muscles is communicated through certain

chemicals in the body, which are known as chemicalmessengers.

7. Some chemical substances which remove the excessacid in the stomach and raise the pH at appropriatelevel are called antacids.

e.g.,sodium hydrogen carbonate, a mixture ofaluminium and magnesium hydroxide, etc.

8. Tranquilizersare a class of chemical compounds usedfor the treatment of stress and mild or severe mentaldiseases. These form an essential component ofsleeping pills Chlorodiazepoxide, meprobamate aremild tranquilizers and are used in relieving pain. Equanilis used in controlling depression and hypertension.

9. Barbiturates (Derivatives of barbituric acid), likeveronal, amytal, nembutal, luminal, seconal, valium,serotonin, etc. are used as hypnotic, i e. ., sleepproducing agents.

10. Analgesics abolish or reduce pain without causingimpairment of consciousness, mental confusion,incoordination or paralysis or some other disturbancesof nervous system. Aspirin and paracetamolbelong tothe class of (non-narcotic or non-addictive or non-habitforming) analgesics. Morphine and many of itshomologues are narcotic or habit forming analgesics.

11. Chemical substance used to bring down bodytemperature at the time of high fever are calledantipyretics e.g., aspirin, paracetamol, etc.

12. Antibioticsare the substance produced wholly or partly

by chemical synthesis, which in low concentrationsinhibit the growth or destroy microorganisms byintervening in their metabolic processes.

Arsphenamine (salvarsan) was the first effectiveantibiotic for syphilis.

13. Antibiotics which kil l or inhibit a wide range ofgram-positive and gram-negative bacteria are calledbroad spectrum antibioticsand those effective againstgram-positive or gram-negative bacteria are callednarrow spectrum antibiotics. Penicillin G is a narrowspectrum antibiotics while ampicillin and amoxycillin aresynthetic penicillins and are broad spectrum antibiotics.Chloramphenicol is one of the broad spectrumantibiotics and can be given orally to treat typhoid,

dysentery, acute fever and pneum

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Revision Notes Chemistry XII