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IS MATTER AROUND US PURE?
Chemical classification of matter [NOTE: to be done in L.H.S ]
I. a) PURE SUBSTANCE: Pure substances are elements and compounds having uniform
composition of similar atoms or molecules in a fixed ratio.
Eg: ELEMENTS: Substance having similar kind of atoms. Eg: H, O, Na, Cl
COMPOUNDS: Pure substances in which two or more elements (dissimilar atoms)
combine chemically in a fixed ratio by weight. Eg: CuSO4, BaSO4, NaOH, H2O.
b) MIXTURE: Two or more substances which remain together and can be separated by
simple physical methods.
TYPES OF MIXTURES:
i) Homogeneous mixtures: Mixtures with uniform composition.
Eg: air, alloys, salt solution, lemonade, alcohol + water
ii) Heterogeneous mixtures: Mixtures with non – uniform composition.
Eg: soil+ water, oil +water, S + Fe fillings, chalk+water, smoke (mixture of
carbon particles in air)
Tabulate the differences between compounds and mixtures with examples
Compounds Mixtures
1. Compounds are formed as a result of chemical
reactions between two or more elements .
1. They are formed by simple mixing of 2 or
more constituents
2. Components of a compound are always
present in a definite ratio by mass
2.The components of a mixture may be present
in any ratio.
2. Homogeneous in nature 3. Can be homogeneous or heterogeneous.
4. Properties of a compound are entirely different
from its constituents.
4. Properties of a mixture are same as those of
its constituents.
5. Components of compound can be separated by
Chemical methods.
5. Components of a mixture can be
separated by physical methods.
6.Melting and boiling points of a compound are
fixed
6. Melting and boiling points of a mixture are
usually not fixed.
Tabulate the differences between Elements and Compounds with examples
Element Compound
1.Consists of same kind of atoms. 1.Dissimilar atoms combine in a fixed ratio.
2.Elements cannot be broken down. 2.Compounds can be broken by chemical methods
3.H,Na,Li,Pb…. 3.CO2,SiO2,H2SO4….
Q1. Air is considered to be mixture. Justify i) Air is a homogeneous mixture of different gases (N2 , O2 , CO2 , watervapour
, noble gases)
ii) The component gases retain their individual properties
iii) The components of air can be separated by physical methods (liquefaction
followed by fractional distillation)
Home work: Q The mixture of sulphur and iron filling is considered to be heterogeneous
in nature. Give reasons.
Q2. CO2 is a compound. Prove it.
i) CO2 has C and O in the ratio of 1:2
ii) C and O lose their individual properties after forming CO2.
iii) The components cannot be separated by physical methods.
iv) A compound has fixed melting and boiling point.
Homework: Solve worksheet
II. SOLUTIONS:
➢ It is a homogeneous mixture of two or more substances (also called as true solution)
➢ It has two components solute and the solvent.
Solute +solvent = solution
Eg: i) sugar + water = sugar solution
iii) Iodine + alcohol = Tincture of iodine
➢ Solute: substance which dissolves in solvent to form solution (present in less
amount)
➢ Solvent: substance in which solute dissolves to form solution (present in larger
amount)
Eg: water of sugar solution
TYPES OF SOLUTIONS:
1. Saturated solution: A solution in which no more solute can be added to form a
true solution.
Amount of solute = solubility
Eg: 36gms of NaCl dissolves completely in 100gm of water at 20OC
Note: Solubility depends on temperature.
➢ Solubility of solid in liquid increases with increase in temperature.’
➢ Solubility of a gas in liquid decreases with increase in temperature.
2. Unsaturated solution: A solution in which more solute can be added to make it
saturated.
Amount of solute < solubility
Eg: 20gm of NaCl is dissolved in 100ml of water at 20OC.
3. Super saturated solution: A solution in which some solute is left undissolved.
Amount of solute > solubility
Eg: 50gms of NaCl is present in 100ml of water at 20OC.
Tabulate the difference between [NOTE: to be done in L.H.S]
a) Homogeneous mixture and Heterogeneous mixtures with examples
b) Saturated and Unsaturated solutions with
examples CONCENTRATION OF SOLUTION:
➢ The amount of solute present in a solution.
➢ Concentration can be expressed in m/m %, v/v %, m/v%
➢ Concentration of solution = 𝑎𝑚𝑜𝑢𝑛𝑡 𝑜𝑓 𝑠𝑜𝑙𝑢𝑡𝑒 𝑎𝑚𝑜𝑢𝑛𝑡 𝑜𝑓 𝑆𝑜𝑙𝑢𝑡𝑖𝑜𝑛
➢ Solute + solvent = solution
% concentration = 𝑎𝑚𝑜𝑢𝑛𝑡 𝑜𝑓 solute X 100
𝑋 100
𝑎𝑚𝑜𝑢𝑛𝑡 𝑜𝑓 𝑠𝑜𝑙𝑢𝑡𝑒 + 𝑎𝑚𝑜𝑢𝑛𝑡 𝑜𝑓 𝑠𝑜𝑙𝑣𝑒𝑛𝑡
NUMERICAL PROBLEMS:
1. 10gm of CuSO4 is added to 90ml water to make a saturated solution. Find the %
concentration of the solution.
Solution:
Given CuSO 4 (solute) = 10gm
Water (solvent)= 90ml [or 90gm]
% concentration =?
% concentration = 𝑎𝑚𝑜𝑢𝑛𝑡𝑜𝑓 𝑠𝑜𝑙𝑢𝑡𝑒 𝑎𝑚𝑜𝑢𝑛𝑡 𝑜𝑓 𝑠𝑜𝑙𝑢𝑡𝑒 + 𝑎𝑚𝑜𝑢𝑛𝑡 𝑜𝑓 𝑠𝑜𝑙𝑣𝑒𝑛𝑡
𝑋 100.
% concentration = 10
10 + 90 𝑋 100 = 10 %.
2. 30% of HNO3 is prepared by adding nitric acid to 200ml distilled water. Find the
amount of acid used?
Solution:
Given % concentration = 30%
Water (solvent) = 200ml
Acid (solute) = x ml
% concentration = 𝑎𝑚𝑜𝑢𝑛𝑡𝑜𝑓 𝑠𝑜𝑙𝑢𝑡𝑒 𝑎𝑚𝑜𝑢𝑛𝑡 𝑜𝑓 𝑠𝑜𝑙𝑢𝑡𝑒 + 𝑎𝑚𝑜𝑢𝑛𝑡 𝑜𝑓 𝑠𝑜𝑙𝑣𝑒𝑛𝑡
𝑋 100.
30 % = 𝑥 𝑥+200
𝑋 100
30 (x+200) = 100x
6000 = 100x -30x
x = 6000 / 70 = 85.7ml
3. How will you prepare 10% of 500ml sugar solution?
Solution:
Given % concentration = 10%
Solution = 500ml
Solute = x gm
Concentration of solution = 𝑎𝑚𝑜𝑢𝑛𝑡 𝑜𝑓 𝑠𝑜𝑙𝑢𝑡𝑒 𝑎𝑚𝑜𝑢𝑛𝑡 𝑜𝑓 𝑆𝑜𝑙𝑢𝑡𝑖𝑜𝑛
𝑋 100
10 = x/ 500 X 100
(Sugar) x = 50gm
Solvent (water) = solution - solute
= 500- 50
= 450 ml.
Homework questions:
Q1. 32ml of kerosene is added to petrol to prepare 20% of its solution. Find the amount of
petrol required?
(Hint kerosene (solute) petrol (solvent)
Q2. Solve Pg 17 eg2.1
Home work: solve worksheet questions of above sums of concentration.
Properties of True Solutions:
➢ Homogeneous mixture
➢ Solute particle size less than 1nm [ 1 nm = 10 -9
m]
➢ Solute particles are very small in size and cannot be separated by filtration but can be separated
by evaporation.
➢ They are stable. Solute particles do not separate on leaving undisturbed.
➢ Does not show tyndall effect
➢ Examples: Sugar solution, CuSO4 solution
TYNDALL EFFECT: The phenomenon of scattering of light rays by the particles in the medium so
that the path of the light rays can be seen.
Eg: 1. Sunlight passing through canopy of a dense forest gets scattered.
2. Light seen from the projector
3. Light from the car head light during night times.
SUSPENSIONS:
➢ Heterogeneous mixture
➢ Solute particle size is greater than 100nm.
➢ Solute particles can be seen with the eyes.
➢ Suspensions are unstable, solute particles settle down when left undisturbed.
➢ They show tyndall effect in the disturbed state, but does not show tyndall effect When the
particles settle down.
➢ Solute particles are separated by simple physical methods like filtration.
➢ Examples: sulphur + iron filling
Sand + water, chalk powder + water
COLLOIDS:
➢ Heterogeneous mixture in which solute particle size is in between 1 nm and 100nm.
➢ Brownian movement: particles of colloid move in zig - zag motion giving it a blurred
appearance. This movement is called Brownian movement.
➢ A colloid has two component
i) Dispersed phase (component in less quantity - solute)
ii) Dispersion medium (component in larger quantity - solvent)
➢ Solute particles do not settle down when left undisturbed.
➢ Particles cannot be separated by ordinary filter paper, but can be separated by special techniques
- Ultra filtration, centrifugation
➢ Colloids show tyndall effect
➢ Examples starch solution, egg albumin + water, blood, milk etc.
Home work: solve blue box questions pg no 18
TYPES OF COLLOIDS:
Depending on the physical state of the dispersed phase and dispersing medium colloids are classified
into 8 types:
1. Sol: A colloid of solid dispersed phase in liquid / solid dispersing medium. Eg: starch solution, mud
water, milk of magnesia etc.
2. Emulsion: A colloid of liquid dispersed phase in liquid dispersing medium.
Eg : milk, face cream
3. Aerosol: A colloid of solid / liquid dispersed phase in gas dispersing medium. Eg fog, clouds,
smoke, automobile exhaust.
4. Foam: A colloid of gas dispersed phase in solid / liquid dispersing medium. Eg: rubber, sponge ,
shaving cream
5. Gel: A colloid of liquid dispersed phase in solid dispersing medium. Eg: jelly, cheese, butter
Home work: Draw table 2.1 and write common examples of colloids.
SEPERATION OF MIXTURES:
Principle: the components of a mixture can be separated based on the difference in the physical and
chemical properties between the different components of the mixture.
I. Separation of coloured component (Dye) from ink: - Evaporation
Principle: Evaporation technique is applied non - volatile (dye) from volatile water (ink)
Procedure:
➢ Take a beaker half filled with water.
➢ Place watch glass on the mouth of the beaker and put few drops of ink.
➢ Place the beaker on a tripod stand with a wire gauze.
➢ Start heating the beaker. Steam formed in the beaker will heat the watch glass.
➢ Water evaporates from ink leaving behind the dye in the watch glass.
Application:
➢ To obtain salt from sea water.
[Home work: Draw fig.2.5 pg.19 in L.H.S]
II. Separation of cream from milk. (Centrifugation)
Principle: to separate denser particles from lighter particles in a medium.
Procedure:
➢ Take some full cream milk in a test tube and place in a centrifuge machine.
➢ Run the centrifuge machine for about 2 minutes.
➢ The lighter cream particles of milk move to the surface and the denser part of the milk remains in
the bottom.
Application:
1. To separate cream from milk
2. To test urine and blood samples in diagnostics laboratories.
3. Used in washing machines to dirt and also squeeze water from wet clothes.
III. Separation of immiscible liquids:
Immiscible Liquids: Liquids that do not dissolve in each other. Eg: oil and water, petrol + water
Principle: Separating funnel is used to separate immiscible liquids based on their difference in
densities.
Procedure:
➢ Take a mixture of kerosene and water each 50ml in a separating funnel and allow it to stand
undisturbed for some time.
➢ We observe that lighter kerosene floats on heavier water
➢ If we open the stopcock, water drips out of the funnel slowly. Close the stopcock as the kerosene
Applications:
1. To separate a mixture of oil and water
2. To separate lighter slag from the heavier molten iron during the extraction of iron from its ore.
Home work: draw fig 2.6 from pg 20.
IV. To separate a mixture of sodium chloride and ammonium chloride [SUBLIMATION]
Principle: sublimation technique is used to separate a mixture of sublimable and non - sublimable
salts.
Procedure:
➢ Take a mixture of NaCl and NH4Cl in a china dish and place it on a tripod stand with a wire
gauze.
➢ Put an inverted funnel over the china dish and plug the stem of the funnel with cotton.
➢ Start heating the china dish slowly.
➢ We observe dense white fumes of NH4Cl emitting out.
➢ These fumes cool and condense in the inner walls of the funnel which can be scrapped out and
NaCl remains in the china dish.
Uses: to separate sublimable and non - sublimable salts.
Note: Draw fig 2.7 from pg no 20
V. SEPARATION OF DIFFERENT COLOUR DYES FROM BLACK INK.
Principle: Chromatography technique is applied to separate different dyes (solutes) that dissolve in ink
(same solvent) based on the difference in solubility.
Procedure:
➢ Take a filter paper and cut it into a thin strip.
➢ Draw a line 3cm approximately above from one end and then put a drop of black ink in the centre
of the line and dry.
➢ Lower the filter paper in the beaker half filled with water in such a way that the ink does not
touch the surface of water.
➢ Later we find that different dyes present in the ink absorb water, rises up to different heights on
the filter paper due to difference in their solubility.
Applications:
➢ Separation of colors from dyes
➢ Pigments from plant parts.
➢ To test drugs in blood.
Note: Draw fig 2.8 from pg no 21 in L.H.S
VI. Separation of miscible liquids:
Note: Liquids which dissolve or mix in each other are called miscible liquids. Eg alcohol and water,
Acetone and water.
A) SIMPLE DISTILLATION:
Principle: separation of miscible liquids which has more difference in their boiling points (more than
25oC)
Procedure:
➢ A mixture of acetone and water is taken in a distillation flask fitted with a rubber cork.
➢ The rubber cork is fixed to a thermometer and a delivery tube which is in turn connected to a
water condenser.
➢ Steam the mixture slowly by using Bunsen burner.
➢ We observe that acetone having lower boiling point vaporizes first and condenses in the
condenser4 and is collected separately.
➢ Water having higher boiling point in the distillation flask.
➢ Thermometer records the constant boiling point of the two liquids.
USES:
➢ To separate miscible liquids having large difference in their boiling points.
[Note: Draw fig 2.9 from pg no 2 in L.H.S]
B) FRACTIONAL DISTILLATION:
Principle: Separation of two miscible liquids having less difference in their boiling points (less than
25oC )
Procedure:
➢ Take the mixture of liquids in a distillation flask fitted with a condenser, thermometer to
fractionating column.
➢ The fractionating column is filled with glass beads. These beads provide surface area for the pure
vapours to move and cool into the condenser and avoid mixing of vapors.
➢ Liquids with low boiling points starts vaporizing first and are condensed in the condenser which
are collected as pure liquids after passing through the fractionating column.
➢ Thermometer connected to the fractionating column records the boiling points of liquids
vaporizing,
➢ In this way mixture of several liquids can be separated.
Uses:
➢ Crude oil / petroleum is refined and separated into different petro chemicals by the process of
fractional distillation.
➢ Separation of gases from liquid air.
[Note: Draw fig 2.10 from pg no 22 in L.H.S]
VII. LIQUIFACTION OF AIR (separation of gases from liquid air)
Principle: Conversion of air to liquid under high pressure and low temperature followed by fractional
distillation.
Air
Filter to remove solid dust particles
Compressed and cooled by applying high pressure and low temperature
Liquid air
Fracttional distillation
O2 , Ar , N2 (seperates out first)
(-183O C) (-186OC) (-196OC)
Increasing order of boiling point
N2 < Ar < O2
VIII. Crystallisation or purification of salts.
Principle: purification of salts by filtration on followed by evaporation.
Procedure:
➢ Take 10gm of impure CuSO4, in a beaker and add water to dissolve the salt to prepare a saturated
solution.
➢ Filter the solution to remove undissolved impurities.
➢ Take a filtered solution in the china dish and boil it to make a saturated solution. Cool the
solution slowly.
➢ Pure crystals of CuSO4 are formed in the liquid at the bottom which can be obtained by the
decantation of top liquid.
Uses:
➢ To purify common salt
➢ To purify alum and sugar
IX. WATER PURIFICATION SYSTEM IN WATER WORKS:
STEP 1 : Reservoir
STEP 2 : Sedimentation tank [to remove denser particles]
STEP 3 : Loading tank [to remove suspended impurities]
STEP 4 : Filtration tank [to remove lighter impurities]
STEP 5 : Chlorination tank [to kill microbes]
STEP 6 : Supply
PHYSICAL AND CHEMICAL CHANGES:
PHYSICAL CHANGE CHEMICAL CHANGE
Reversible change Irreversible change
Change in physical properties only Change in both physical and chemical properties
No new substance is formed New substance is formed
Temporary change Permanent change
Eg: sublimation, crystallisation, liquifaction etc. Eg: corrosion of metals, digestion of food,
burning of fuels.
NOTE: Burning of candle is both physical and chemical change
PURE SUBSTANCE:
➢ Substances which contain only one kind of particles.
➢ They are classified into elements (same kind of atoms) and compounds (same kind of molecules)
➢ Elements are classified into metals, non - metals and metalloids.
PROPERTIES OF METALS:
➢ Metals are the elements which loses electrons to form cations.
➢ Metals are generally solids except mercury (liquid metal) at room temperature.
➢ Good conductors of heat.
Silver - best, lead and mercury - poor conductors
➢ Good conductors of electricity
Silver - best, mercury and iron - poor conductors
➢ They are malleable and ductile.
Gold and silver - best, zinc - brittle
➢ Lustrous and sonorous
Eg: lead, tin, nickel etc.
PROPERTIES OF NON - METALS:
➢ Non - metals are the elements that gain electrons to form anion.
➢ All are solids and gases except liquid bromine
➢ Bad conductors of heat
➢ Bad conductors of electricity except graphite
➢ Non - malleable and non - ductile
➢ Non - sonorous
➢ Generally, non - lustrous except graphite
➢ Eg: Oxygen, hydrogen, nitrogen, carbon, Sulphur, etc.
METALLOIDS:
Elements having properties of both metals and non – metals.
Eg: boron, silicon, arsenic, silicon, germanium etc.