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CHEM 111: Inleidende Anorganiese enFisiese Chemie

Four Study UnitsStudy Unit 1: Inleiding: Materie en meting - 0 lectures (self study)

Study Unit 2: Atome en elemente - 3 lectures

Study Unit 3: Molekules, ione en verbindings - 5 lectures

Study Unit 4: Chemiese vergelykings en Stogiometrie 8 lectures

Kotz, Treichel & Townsend, gedeeltes van hoofstukke. 1, 2, 3 en 4

Studiegids bl. 1 - 43, Leereenhede 1, 2, 3 & 4

LEERAFDELING ABOUSTENE VAN CHEMIE


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LEEREENHEID 4

CHEMIESE VERGELYKINGSEN STOGIOMETRIE

KT & T, bl. 112 121 en 158 - 174

Studiegids, Leergedeeltes 4.1 4.8, bl. 31 - 46


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OUTCOMES for Study Unit 4.1

Study guide p. 33 - 34.

KT&T, pp. 113 - 121.

Balansering en interpretasie van chemiese vergelykings

UITKOMSTENa voltooiing van hierdie leergedeelte behoort jy:

te weet wat n gebalanseerde chemiese vergelyking is.

die inligting te interpreteer wat deur 'n gebalanseerdechemiese reaksie weergegee word.

'n eenvoudige chemiese vergelyking te balanseer.


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CHEMICAL REACTIONSCHEMICAL REACTIONS

Reactants: Zn + IReactants: Zn + I22 Product: Zn IProduct: Zn I22


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Chemical EquationsChemical EquationsDepict the kind ofDepict the kind ofreactantsreactants andandproductsproducts and their relative amountsand their relative amountsin a reaction.in a reaction.

44 Al(s) +Al(s) + 33 OO22(g) (g) 22 AlAl22OO33(s)(s)

StoichiometricStoichiometric coefficientscoefficients

Physical states of reagents and productsPhysical states of reagents and products

Molverhoudingtussen reaktanteen produkt(e)


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Reaction of hosphorus with ClReaction of hosphorus with Cl22Reaction of hosphorus with ClReaction of hosphorus with Cl22

Notice the stoichiometric coefficients and theNotice the stoichiometric coefficients and the

physical states of the reactants and products.physical states of the reactants and products.


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Reaction of Iron with ClReaction of Iron with Cl22Reaction of Iron with ClReaction of Iron with Cl22

Notice the stoichiometric coefficients and theNotice the stoichiometric coefficients and the

physical states of the reactants and products.physical states of the reactants and products.


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CHEMICAL REACTIONSCHEMICAL REACTIONSAl(s) r2(l) Al2 r6(s)2 3+

a. Name the reactants and products and give their

physical states.

b. What are the stoichiometric coefficients in this equation?

c. If you were to use 8000 atoms of Al, how many molecules

of Br2 are required to consume the Al completely?

AnswersAnswers

a. Reactants = Al and Br2 , Product = Al2Br6Physical states = Al (solid), Br2 (liquid), Al2Br6 (solid)

b. Al = 2, Br2 = 3 and Al2Br6 = 1

c. 12 000 molecules of Br2

Doen in klas


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Chemical EquationsChemical EquationsChemical EquationsChemical Equations

4 Al(s) + 3 O4 Al(s) + 3 O22(g) 2 Al(g) 2 Al22OO33(s)(s)

TTHISHIS EQUATIONEQUATION MEANSMEANS::4 Al atoms + 3 O4 Al atoms + 3 O22 moleculesmolecules ----givegive 2 molecules of Al2 molecules of Al22OO33

IITT ALSOALSO MEANSMEANS::

4 moles of Al + 3 moles of O4 moles of Al + 3 moles of O22 ----givegive 2 moles of Al2 moles of Al22OO33


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Chemical EquationsChemical EquationsChemical EquationsChemical Equations

Because the same atoms are present in aBecause the same atoms are present in a

reaction at the beginning and at the end, thereaction at the beginning and at the end, the

amount of matter in a system does notamount of matter in a system does not

change.change. TheThe Law of the Conservation of MatterLaw of the Conservation of Matter

2HgO(s)2HgO(s) ------> 2 Hg(> 2 Hg(liqliq) + O) + O22(g)(g)


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Because of the principle of theBecause of the principle of the

conservation of matterconservation of matter,,

anan equation must beequation must bebalancedbalanced..

It must have the sameIt must have the same

number of atoms of thenumber of atoms of thesame kind on both sides.same kind on both sides.

Chemical EquationsChemical Equations

Lavoisier, 1788Lavoisier, 1788


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Balancin Equations viaBalancin Equations via

inspectioninspection

Balancin Equations viaBalancin Equations via

inspectioninspection

___ Al(s) + ___Br___ Al(s) + ___Br22((liqliq)) ------> ___ Al> ___ Al22BrBr66(s)(s)32


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Balancin Equations viaBalancin Equations viainspectioninspectionBalancin Equations viaBalancin Equations viainspectioninspection

___C___C33HH88(g) + ___ O(g) + ___ O22(g) ___CO(g) ___CO22(g) + ___ H(g) + ___ H22O(g)O(g)1 5 3 4


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Doen in klas

C r O 2 Cr2O 3(g)(s) (s)+4 3 2

Balanseer die vol ende ver el kin s

AlCl3 Na H Al( H)3 NaCl(s) (aq) (aq)(s) ++ 33


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Doen in klas

Write a balanced chemical equation for the productionof ammonia, NH3 ( ), from N2 ( ) and H2 ( )

N2(g) H2(g) NH3(g)+

Balanseer nou vergelyking

N2(g) H2(g) NH3(g)+ 3 2


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Write a balanced chemical equation for thecombustion of liquid tetraeth llead, b(C2H5)4 .The products of combustion are bO(s), H2O( )

and CO2( ).

Doen in klas

2 227 20 16Pb(C2H5)4 2 Pb (s) H2 (g) C 2(g)+ + +

Pb(C2H5)4 2 Pb (s) H2 (g) C 2(g)+ + +


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Study guide p. 35 - 36.

KT&T, pp. 158 - 162.

Sto iometrie


Stogiometriese berekenings te kan uitvoer op 'n gebalanseerdereaksievergelyking.


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Stoigiometriese koeffisiente:Stoigiometriese koeffisiente: koeffisiente inkoeffisiente inn gebalanseerde vergelykingn gebalanseerde vergelyking

What is meant by the wordWhat is meant by the wordStoichiometryStoichiometry

Die verwantskap tussen die hoeveelheidDie verwantskap tussen die hoeveelheidreagense en produktereagense en produkte

44Al(s) +Al(s) + 33OO22 22AlAl22OO33(s)(s)


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VOORBEELDVOORBEELD

2,68 g2,68 g

(a) 4Fe(s) + 3O(a) 4Fe(s) + 3O22(g)(g) 2Fe 2Fe22OO33(s)(s)

(b) 3,819 g Fe(b) 3,819 g Fe22OO33

(c) 1,150 g O(c) 1,150 g O22


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Consider the following unbalanced equation.Consider the following unbalanced equation.

BaClBaCl22(aq) + AgNO(aq) + AgNO33(aq)(aq) AgCl(s) + Ba(NOAgCl(s) + Ba(NO33))22(aq)(aq)

1.1. Write the balanced equationWrite the balanced equation

2.2. What mass of AgNOWhat mass of AgNO33, in grams, is required for complete, in grams, is required for complete

reaction with 0,156 g of BaClreaction with 0,156 g of BaCl22??

3. What mass of AgCl in grams, is produced?3. What mass of AgCl in grams, is produced?

(a) BaCl(a) BaCl22(aq) +(aq) + 22AgNOAgNO33(aq)(aq) 22AgCl(s) + Ba(NOAgCl(s) + Ba(NO33))22(aq)(aq)

(b) 0,255 g AgNO(b) 0,255 g AgNO33

(c) 0,215 g AgCl(c) 0,215 g AgCl

Doen in KlasDoen in Klas


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Doen in klasDoen in klas

Methane, CHMethane, CH44, burns in oxygen., burns in oxygen.

a)a) What are the products of the reaction?What are the products of the reaction?

b)b) Write the balanced equation for the reaction.Write the balanced equation for the reaction.

c)c) What mass of OWhat mass of O22, in grams, is required for complete, in grams, is required for complete

combustion of 25,5 g of methane?combustion of 25,5 g of methane?

d)d) What is the total mass of products expected from theWhat is the total mass of products expected from the

combustion of 25,5 g of methane?combustion of 25,5 g of methane?

(a)(a) COCO22(g) & H(g) & H22O(O(ll))

(b)(b) CHCH44(g) + 2O(g) + 2O22 CO CO22(g) + 2(g) + 2HH22O(O(ll))

(c) 101.725 g O(c) 101.725 g O22

(d) 127.244 g(d) 127.244 g


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Study guide p. 37.

KT&T, pp. 163 - 167.

Beperkende Rea ense


die beperkende reagens uit twee reagense te kan bereken.


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InIn chemiesechemiese reaksiesreaksies isis diedie doeldoel omom diedie maksimummaksimum opbrengsopbrengsvanvan nn bruikbarebruikbare produkproduk tete verkryverkry..

OmOm ditdit tete versekerverseker::

word dieword die reagensreagens watwat nienie soso duurduurisis nienie inin oormaatoormaat in diein die

reaksiereaksie gebruikgebruik,,

omom tete versekerverseker datdat diedie duurduur ((beperkendebeperkende)) reagensreagens volledigvolledig

omgesitomgesit wordword nana diedie produkproduk..


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Identifiseer die beperkende uitgangstof/reagens.Wat is die massa TiCl4 wat gevorm word?

Ti 2(s) + 2Cl2(g) + C(s)p TiCl4(P) + C 2(g)

TiCl4 is n belangrike industrile chemiese stof wat berei

kan word vanaf onsuiwer TiO2 tydens reaksie met koolstof

en chloorgas. In 'n bereiding is met gelyke hoeveelhede

chloorgas en koolstof (125 g elk) en n oormaat TiO2 begin.


ClCl22 beperkendbeperkend 167,017 g TiCl167,017 g TiCl44


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2020 pittepitte %% OpbrengsOpbrengs = (16/20) x 100%= (16/20) x 100%= 80%= 80%

16 pop16 pop


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TeoretieseTeoretiese vs Werklike Ovs Werklike Opbrengspbrengs

Die teoretiese opbrengsteoretiese opbrengs is die hoeveelheid

produk wat uit 'n chemiese reaksie verkry

behoortbehoort te word.

Tydens 'n chemiese reaksie kan 'n gedeeltegedeelte

van die produkproduk(te)(te) verloreverlore gaan as gevolg van

praktiese probleme.

The real yield / werklikereal yield / werklike opbrengsopbrengs is therefore

not equal to the theoretical yieldtheoretical yield.


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PersentasiePersentasie OOpbrengspbrengs

Om dieOm die doeltreffendheiddoeltreffendheid vanvan 'n'n chemiesechemiese

reaksie te bepaalreaksie te bepaal

To calculate the effectiveness of a chemicalTo calculate the effectiveness of a chemical

reactionreaction

%100XopbrengsTeoretieseopbrengsWerklike=opbrengsePersentasi

Implikasies vir Industrie:Implikasies vir Industrie:

ProduksieProduksie

KosteKoste


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Metanol kan ontbind word om waterstofgas te lewer watas brandstof gebruik kan word.

CH3OH(P) p 2H2(g) + CO(g)

(a) Indien 125125 gg metanolmetanol ontbind word, wat is die

teoretieseteoretiese opbrengsopbrengs van waterstof?

(b) If only 1313..66 gg hydrogenhydrogen is obtained, what is the

perpercentagecentage yieldyield of the gas?


(a)(a) 15.762 g15.762 g

(b)(b) 86.283 %86.283 %


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Study guide p. 39.

KT&T, pp. 169 - 174.

Ver el kin en Chemiese Analise


nn mengselmengsel vanvan verbindingsverbindings tete analiseeranaliseer..

deurdeur verbrandingverbranding vanvan diedie verbindingverbinding,, diedie formuleformule vanvan diedie verbindingverbinding

tete bepaalbepaal..


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Berekeningstegniek No 1Berekeningstegniek No 1


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StoigiometrieStoigiometrie wordword deurdeur chemicichemici gebruikgebruik omom diedie

suiwerheidsuiwerheid vanvan verbindingsverbindings tete bepaalbepaal..

BvBv.. diedie analiseanalise vanvan steenkoolsteenkool omom diedie swawelinhoudswawelinhoud

tete bepaal,bepaal, isis nn aksieaksie watwat daagliksdaagliks byby fabriekefabrieke

uitgevoeruitgevoer wordword watwat brandstof brandstof uituit steenkoolsteenkool

vervaardigvervaardig..

Gebruik stoigiometrie om n mengsel vanGebruik stoigiometrie om n mengsel van

verbindings te analiseer.verbindings te analiseer.


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Analiese prosedure om swawelinhoud inAnaliese prosedure om swawelinhoud in

steenkool te bepaal:steenkool te bepaal:Swawel in steenkool word gereduseer na HSwawel in steenkool word gereduseer na H22S:S:

S(steenkool) + reduksiereagens HS(steenkool) + reduksiereagens H22SS

Bv.Bv. Die analise van 1,00 g steenkool wat swawel bevatDie analise van 1,00 g steenkool wat swawel bevat

lewer 0,0130 g Hlewer 0,0130 g H22S.S.

Vraag:Vraag:Bereken die % S in die monster steenkoolBereken die % S in die monster steenkool

1,223% S1,223% S


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91,94 % CuSO91,94 % CuSO44.5H.5H22OO


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AA 22,,634634 gg samplesample containingcontaining CuClCuCl22..22HH22OO andand otherother materialsmaterials

waswas heatedheated.. TheThe samplesample massmass afterafter heating,heating, toto drivedrive offoff thethe

waterwater attachedattached toto CuClCuCl22,, waswas 22,,125125 gg.. WhatWhat waswas thethe massmass

persentpersent ofof CuClCuCl22..22HH22OO inin thethe originaloriginal sample?sample?


91,154 %91,154 %


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GebruikGebruik stoigiometriestoigiometrie omom diedie formuleformule van nvan n

verbindingverbinding tete bepaalbepaal deurdeur verbrandingverbranding van dievan die

verbindingverbinding..

Use stoichiometry to determine the formula of aUse stoichiometry to determine the formula of a

compound throughcompound through combustion of thecombustion of the

compoundcompound..


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p 162 & 163p 162 & 163

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Leereenheid+4 +Leergedeeltes+4.1+Tot+4.5