ib chemistry limiting, excess, theoretical and percentage yield
TRANSCRIPT
http://lawrencekok.blogspot.com
Prepared by Lawrence Kok
IB Chemistry on Limiting, Excess, Percentage Yield and Ionic Equations
1Pb(NO3)2(aq) + 2KI(aq) → 1PbI2(s) + 2KNO3(aq)
Lead + Potassium → Lead + Potassium Nitrate iodide iodide nitrate
Chemical Eqn
Reactant – Left Product – Right Conservation MassTotal Mass reactant = Total Mass product
Mole Ratio - Coefficient of reactant/product
1Pb(NO3)2(aq) + 2KI(aq) → 1PbI2(s) + 2KNO3(aq)1 : 2 → 1 : 2
Word equation Chemical formula
Calcium + hydrochloric → Calcium + carbon + watercarbonate acid chloride dioxide
1CaCO3(s) + 2HCI(aq) → 1CaCI2(aq) + 1CO2(g)
+ 1H2O(l)
Product – Right Reactant – Left Conservation MassTotal Mass reactant = Total Mass product
1 : 2 → 1 : 1 : 1 Mole Ratio - Coefficient of reactant/product
Physical state/ symbol
(s) – solid(I) - liq(g) – gas(aq) – aqueous ∆ - heatppt –
precipitate/solid↔ - reversible
Physical state/ symbol
(s) – solid(I) - liq(g) – gas(aq) – aqueous ∆ - heatppt –
precipitate/solid↔ - reversible
Mass reactants (Pb(NO3)2 + KI) = 15.82
Mass products (PbI3 + KNO3) = 15.82
AfterBefore
Chemical rxn Matter is neither created nor destroyed Undergoes physical/chemical change.
LAW of conservation of mass.
Mole proportion/ratio (reactant) →
(product) 1 : 2 → 1
: 2
Concept Map
represented by
1Pb(NO3)2(s) + 2NaI(aq) → 1PbI2(s) + 2NaNO3 (aq)
Limiting reactant Use up first
Limit products formRxn stop if all used up
Excess reactant left over
remains behind
Percentage Yield mass of Actual Yield x 100%mass of Theoretical Yield
Theoretical yieldMax amt prod form if rxn complete
Stoichiometry ratio Assume all limiting reagent used
up
Actual yieldAmt of prod formed
experimentallyLess than theoretical yield due to experimental error
Rxn StoichiometryQuantitative relationship bet quantities react/
prodFind quantities/amt (mass, mole, vol)
Predict how much react and amt prod formChemical rxn react in definite ratio
Chemical Change
Chemical Equation
Balanced Chemical equation
Molecular Eqn
CompleteIonic Eqn
Net Ionic Eqn
1Pb(NO3)2(s) + 2NaI(aq) → 1PbI2(s) + 2NaNO3 (aq)
1Pb2+(aq) + 2NO3
-(aq) + 2Na+
(aq) + 2I-(aq) → 1PbI2(s) + 2Na+
(aq)
+ 2NO3-(aq)
1Pb2+(aq) + 2CI-
(aq) → 1PbCI2(s)
Limiting and Excess
Which is limiting and excess ?
How many hot dog with 6 bun and 3 hot dog?
Stoichiometric ratio 1 mol (bun) : 1 mol (hot dog) → 1 mol
+5 5 5
+
No Excess No limiting
Excess - BunLimiting - Hot dog are used up
Both hot dog and bun used up
How many burger with 12 bun and 6 patties?
+ +
Stoichiometric ratio 2 mol (bun) : 1 mol (burger) → 1 mol
No Excess No limiting
Limiting reactant Use up first, limit the prod
formRxn stop if all used up
Excess reactant Left over, remain behind
1Zn (s) + 2HCI (aq) → 1ZnCI2(aq) + 1H2(g)
Mole ratio1 : 2 → 1: 1
Moles reactant given, which is limiting and excess ?
Which is limiting and excess ?
1st method
2nd method
0.30 mol Zn + 0.52 mol HCl add
1 mol Zn → 2 mol HCI0.30 mol Zn → 2 x 0.30 mol HCI = 0.60 mol HCI needed = 0.52 mol HCI added (HCI – limiting)
0.52 mol HCI0.30 mol Zn
Reactant that produce least amt product → will be limiting
Assume Zn limiting 1 mol Zn → 1 mol H2 gas0.3 mol Zn → 1 x 0.3 = 0.3 mol H2
Assume HCI limiting 2 mol HCI → 1 mol H2 gas0.52 mol HCI → 1 x 0.52 = 0.26 mol H2 2
Simulation on limiting/excess
1Pb(NO3)2(s) + 2NaI(aq) → 1PbI2(s) + 2NaNO3 (aq) Mole ratio1 : 2 → 1: 2
Simulation on limiting/excess
10 g Pb(NO3)2 + 10 g NaI added
0.0302 mol Pb(NO3)2 + 0.0667 mol NaIWhich is limiting and excess ?
1 mol Pb(NO3)2 → 2 mol NaI0.0302 mol Pb(NO3)2 → 2 x 0.0302 mol NaI = 0.0604 mol NaI needed = 0.0667 mol NaI add (NaI excess)
Mass = 10.0RMM 149.9 = 0.0667 mol
Mass = 10.0RMM 331.2= 0.0302 mol
1st method
2nd methodReactant that produce least
amt product → will be limiting
Assume Pb(NO3)2 limiting 1 mol Pb(NO3)2→ 1 mol PbI20.0302 mol Pb(NO3)2→ 1x0.0302 mol PbI2
= 0.0302 mol PbI2 Assume NaI limiting 2 mol NaI → 1 mol PbI2 0.0667 mol NaI → 1 x 0.0667 = 0.0334 mol PbI2 2
3rd methodMole ratio method
1 : 2
57.052.03.0
).().(
5.021
).().(
HCIMoleZnMoleHCIMoleZnMole
from eqn
given mass
Ratio higher ↓
Zn excess/HCI limit
1 : 2 → 1 : 1
Limiting and excess ?
Which is limiting and excess ?1st method
2nd method
1 mol Mg → 2 mol HCI0.0256 mol Mg → 0.0512 mol HCI = 0.0512 mol HCI needed = 0.0341 mol HCI added (HCI – limiting)
27.3 ml, 1.25M HCI0.623 g Mg
Reactant that produce least amt product → will be limiting
Assume Mg limiting 1 mol Mg → 1 mol H2 0.0256 mol Mg → 0.0256 mol H2
Assume HCI limiting 2 mol HCI → 1 mol H2 0.0341 mol HCI → 0.01705 mol H2
Simulation on limiting/excess
Simulation on limiting/excess
0.02 mol NaOH + 0.025 mol H2SO4
Which is limiting and excess ?
2 mol NaOH → 1 mol H2SO4 0.02 mol NaOH → 0.01 mol H2SO4
= 0.01 mol H2SO4 needed = 0.025 mol H2SO4 add (H2SO4 excess)
1st method
2nd methodReactant that produce least
amt product → will be limiting
Assume NaOH limiting 2 mol NaOH → 1 mol H2O 0.02 mol NaOH → 0.01 mol H2O
Assume H2SO4 limiting 1 mol H2SO4 → 1 mol H2O 0.025 mol H2SO4 → = 0.025 mol H2O
Mg(s) + 2HCI(aq) → MgCI2(aq) + H2 (g)
0.623 g Mg + 27.3 ml, 1.25M HCI add
Mass = 0.623RMM 24= 0.0256 mol
Mol = M x V 1000= 1.25 x 0.0273= 0.0341 mol
0.0256 mol Mg + 0.0341 mol HCI
2NaOH(aq) + H2SO4(aq) → Na2SO4(aq) + H2O(l)
1 : 2 → 1 : 1 2 : 1 → 1 : 1
100 ml, 0.2M, NaOH + 50 ml, 0.5M H2SO4 add
Mol = M x V 1000= 0.2 x 0.1= 0.02 mol
Mol = M x V 1000= 0.5 x 0.05= 0.025 mol
3rd methodMole ratio method
1 : 2
75.00341.00256.0
).().(
5.021
).().(
HCIMoleMgMoleHCIMoleMgMole
from eqn
given mass
Ratio higher ↓
Mg excess/HCI limit
Limiting and excess ?
Which is limiting and excess ?
1st method
2nd method
2 mol CO → 1 mol O2
2 mol CO → 1 mol O2 = 1 mol O2 needed = 0.5 mol O2 added (O2 – limiting)
Reactant that produce least amt product → will be limiting
Assume CO limiting 2 mol CO → 2 mol CO2 2 mol CO → 2 mol CO2
Assume O2 limiting 1 mol O2 → 2 mol CO2 0.5 mol O2 → 1 mol CO2
Simulation on limiting/excess
Simulation on limiting/excess
0.02 mol NaOH + 0.025 mol H2SO4
Which is limiting and excess ?
2 mol NaOH → 1 mol H2SO4 0.02 mol NaOH → 0.01 mol H2SO4
= 0.01 mol H2SO4 needed = 0.025 mol H2SO4 add (H2SO4 excess)
1st method
2nd methodReactant that produce least
amt product → will be limiting
Assume NaOH limiting 2 mol NaOH → 1 mol H2O 0.02 mol NaOH → 0.01 mol H2O
Assume H2SO4 limiting 1 mol H2SO4 → 1 mol H2O 0.025 mol H2SO4 → = 0.025 mol H2O
Mol = Volume Molar vol = 45.42 = 2 mol 22.4
Mol = Volume Molar vol= 11.36 = 0.5 mol 22.42 mol CO + 0.5 mol O2
2NaOH(aq) + H2SO4(aq) → Na2SO4(aq) + H2O(l)
2 : 1 → 2 2 : 1 → 1 : 1
100ml, 0.2M, NaOH + 50 ml, 0.5M H2SO4 add
Mol = M x V 1000= 0.2 x 0.1= 0.02 mol
Mol = M x V 1000= 0.5 x 0.05= 0.025 mol
2CO(g) + 1O2(g) → 2CO2 (g)
45.42 L CO + 11.36 L O2 add
3rd methodMole ratio method
2 : 1
45.02
).().(
212
).().(
2
2
OMoleCOMoleOMoleCOMole
from eqn
given mass
Ratio higher ↓
CO excess/O2 limit
Which is limiting and excess ?
1st method
2nd method
0.30 mol Zn + 0.52 mol HCl add
1 mol Zn → 2 mol HCI0.30 mol Zn → 2 x 0.30 mol HCI = 0.60 mol HCI needed = 0.52 mol HCI added (HCI – limiting)
0.52 mol HCI0.30 mol Zn
Reactant that produce least amt product → will be limiting
Assume Zn limiting 1 mol Zn → 1 mol H2 gas0.3 mol Zn → 1 x 0.3 = 0.3 mol H2
Assume HCI limiting 2 mol HCI → 1 mol H2 gas0.52 mol HCI → 1 x 0.52 = 0.26 mol H2 2
Simulation on limiting/excess
Simulation on limiting/excess
3rd methodMole ratio method
1 : 2
57.052.03.0
).().(
5.021
).().(
HCIMoleZnMoleHCIMoleZnMole
from eqn
given mass
Ratio higher ↓
Zn excess/HCI limit
Theoretical, Actual and % Yield
1Zn (s) + 2HCI (aq) → 1ZnCI2(aq) + 1H2(g)
1 : 2 → 1 : 1
Mole ratio1 : 2 → 1: 1
Find theoretical yield, cm3 for H2 gasFind % yield if expt yield is 5800 cm3
%2.98%10059025800%
%100.
.exp%.
yield
yieldltheoreticayieldtyield
HCI limiting ↓
Mole ratio2 mol HCI : 1 mol H2
1Zn + 2HCI → 1ZnCI2 + 1H2
2 mol HCI → 1 mol H2
0.52 mol HCI→ 0.26 mol H2
Theoretical yield 1 mol H2 – 22700 cm3
0.26 mol H2 – 5902 cm3
Expt yield = 5800 cm3
Click here tutorial on austute
Which is limiting and excess ?1st method
2nd method
1 mol Mg → 2 mol HCI0.0256 mol Mg → 0.0512 mol HCI = 0.0512 mol HCI needed = 0.0341 mol HCI added (HCI – limiting)
27.3 ml, 1.25M HCI0.623 g Mg
Reactant that produce least amt product → will be limiting
Assume Mg limiting 1 mol Mg → 1 mol H2 0.0256 mol Mg → 0.0256 mol H2
Assume HCI limiting 2 mol HCI → 1 mol H2 0.0341 mol HCI → 0.01705 mol H2
Simulation on limiting/excess
Simulation on limiting/excess
Mg(s) + 2HCI(aq) → MgCI2(aq) + H2 (g)
0.623 g Mg + 27.3 ml, 1.25M HCI add
Mass = 0.623RMM 24= 0.0256 mol
Mol = M x V 1000= 1.25 x 0.0273= 0.0341 mol
0.0256 mol Mg + 0.0341 mol HCI
1 : 2 → 1 : 1
3rd methodMole ratio method
1 : 2
75.00341.00256.0
).().(
5.021
).().(
HCIMoleMgMoleHCIMoleMgMole
from eqn
given mass
Ratio higher ↓
Mg excess/HCI limit
Theoretical, Actual and % YieldFind theoretical yield, cm3 for H2 gasFind % yield if expt yield is 300 cm3
Mg + 2HCI → MgCI2 + H2
HCI limiting ↓
Mole ratio2 mol HCI : 1 mol H2
2 mol HCI → 1 mol H20.0341 mol HCI→ 0.01705 mol H2
Theoretical yield 1 mol H2 – 22700 cm3
0.01705 mol H2 – 387 cm3
Expt yield = 5800 cm3
%5.77%100387300%
%100.
.exp%.
yield
yieldltheoreticayieldtyield
Click here tutorial on chemwiki
Which is limiting and excess ?
1st method
2nd method
2 mol CO → 1 mol O2
2 mol CO → 1 mol O2 = 1 mol O2 needed = 0.5 mol O2 added (O2 – limiting)
Reactant that produce least amt product → will be limiting
Assume CO limiting 2 mol CO → 2 mol CO2 2 mol CO → 2 mol CO2
Assume O2 limiting 1 mol O2 → 2 mol CO2 0.5 mol O2 → 1 mol CO2
Simulation on limiting/excess
Simulation on limiting/excess
Mol = Volume Molar vol = 45.42 = 2 mol 22.4
Mol = Volume Molar vol= 11.36 = 0.5 mol 22.42 mol CO + 0.5 mol O2
2 : 1 → 2
2CO(g) + 1O2(g) → 2CO2 (g)
45.42 L CO + 11.36 L O2 add
3rd methodMole ratio method
2 : 1
45.02
).().(
212
).().(
2
2
OMoleCOMoleOMoleCOMole
from eqn
given mass
Ratio higher ↓
CO excess/O2 limit
Theoretical, Actual and % YieldFind theoretical yield, g for CO2 gas
Find % yield if expt yield is 30 g
2CO + 1O2 → 2CO2
O2 limiting ↓
Mole ratio1 mol O2 : 2 mol CO2
1 mol O2 → 2 mol CO2 0.5 mol O2 → 1 mol CO2
Theoretical yield 1 mol CO2 – 44 g
%1.68%1004430%
%100.
.exp%.
yield
yieldltheoreticayieldtyield
Expt yield = 30 g
Click here tutorial on chemtamu
1st method
2nd method
1 mol CH3COOH → 1 mol C5H11OH0.0596 CH3COOH → 0.0596 C5H11OH = 0.0596 C5H11OH need = 0.0539 C5H11OH add (C5H11OH – limiting)
0.0539 mol C5H11OH0.0596 mol
CH3COOHSimulation on limiting/excess
Simulation on limiting/excess
Mole ratio method1 : 1
1.10539.00596.0
).().(11
).().(
115
3
115
3
OHHCMoleCOOHCHMoleOHHCMole
COOHCHMolefrom eqn
given mass
Ratio higher ↓
CH3COOH excess/C5H11OH limit
Theoretical, Actual and % Yield
CH3COOH + C5H11OH → Ester + H2O1 : 1 → 1 : 1
Mole ratio1 : 1 → 1: 1
Find mass of ester forms if it has 45% yield
gyieldtyieldltheoretica
yieldtyield
15.3%1007.exp%45
%100.
.exp%.
C5H11OH limiting ↓
Mole ratio1 mol C5H11OH : 1 mol Ester
1 mol C5H11OH → 1 mol Ester0.0539 mol C5H11OH→ 0.0539 Ester
Theoretical yield 1 mol Ester - 130 g0.0539 mol Ester – 7 gExpt yield = ????
Click here tutorial on austute
Which is limiting and excess ?
CH3COOH + C5H11OH → Ester + H2O
1st method
2nd method
1 mol CH3COOH → 1 mol C5H11OH0.0596 CH3COOH → 0.0596 C5H11OH = 0.0596 C5H11OH need = 0.0539 C5H11OH add (C5H11OH – limiting)
0.0539 mol C5H11OH0.0596 mol
CH3COOHSimulation on limiting/excess
Simulation on limiting/excess
Mole ratio method1 : 1
1.10539.00596.0
).().(11
).().(
115
3
115
3
OHHCMoleCOOHCHMoleOHHCMole
COOHCHMolefrom eqn
given mass
Ratio higher ↓
CH3COOH excess/C5H11OH limit
Theoretical, Actual and % Yield
CH3COOH + C5H11OH → Ester + H2O1 : 1 → 1 : 1
Mole ratio1 : 1 → 1: 1
Find mole of C5H11OH used if 0.888 mol Ester is needed with a 65% yield
molx
yieldltheoreticayieldtyield
37.1%100888.0%65
%100.
.exp%.
Mole ratio1 mol C5H11OH : 1 mol Ester
1 mol C5H11OH → 1 mol Ester0.888 mol C5H11OH → 0.888 Ester
Expt yield = 0.888 mol
Click here tutorial on austute
Which is limiting and excess ?
CH3COOH + C5H11OH → Ester + H2O
Aspirin, widely used drugs, prepared below Student reacted salicylic acid with excess ethanoic anhydride. Impure solid aspirin was obtained by filtering. Pure aspirin was obtained by
recrystallization.
Find amt, mol, of salicylic acid, C6H4(OH)COOH, used.
Find theoretical yield, in g, of aspirin, C6H4(OCOCH3)COOH.
Find % yield of pure aspirin.
Find % uncertainty in mass of aspirin.
Salicylic acid ethanoic anhydride aspirin
Mass salicylic acid
3.15 ± 0.02g
Mass pure aspirin
2.50 ± 0.02g
%8.60%10011.450.2%
%100.
.exp%.
yield
yieldltheoreticayieldtyield
molMole
MgMassMole
r
0228.013.13815.3
).(
Mole ratio1 mol salicylic acid : 1 mol aspirin
0.0228 mol salicylic acid : 0.0228 mol aspirin
gMassMMoleMass
MgMassMole
r
r
11.47.1800228.0
).(
%80.0int%.
%10050.202.0int%.
yuncerta
yuncerta
limiting
100 g zinc react with 100 g of iodine producing zinc iodide.
Zn + I2 → ZnI2
Find mass of ZnI2 produced
Find, amt of Zn and I2, and determine which reactant is in excess
molZnMole
MgMassZnMole
r
53.137.65
100).(
).().(
molIMole
MgMassIMole
r
394.08.253
100).(
).().(
2
2
Mole ratio1 mol I2 : 1 mol Zn
0.394 mol I2 : 0.394 mol Zn
I2 – limitingZn - excess
Mole – Zn Mole I2
Mole ratio 1 mol I2 : 1 mol ZnI2
0.394 mol I2 : 0.394 mol ZnI2
gZnIMassMMoleZnIMass
MgMassZnIMole
r
r
8.125319394.0).().(
).().(
2
2
2
Copper metal produced by copper(I) oxide and copper(I) sulfide shown below
Mixture of 10 kg of copper(I) oxide and 5 kg of copper(I) sulfide was heated. 2Cu2O + Cu2S → 6Cu + SO2
Find limiting reagent.Mole – Cu2O Mole Cu2S
molOCuMole
MgMassOCuMole
r
9.6914310000).(
).().(
2
2
molSCuMole
MgMassSCuMole
r
4.311595000).(
).().(
2
2
Find maximum mass Cu produced
Mole ratio 2 mol Cu2O : 1 mol Cu2S
69.9 mol Cu2O: 35 mol Cu2SCu2S – limitingCu2O - excess
Mole ratio1 mol Cu2S : 6 mol Cu
31.4 mol Cu2S : 188 mol Cu
gCuMassMMoleCuMass
MgMassCuMole
r
r
1190055.63188).().(
).().(
Student determine Mr of solid monoprotic acid, HA, by titrating with a known mass of acid.
Data shown below.
Find mass of acid and determine its absolute and % uncertainty
Known mass of acid, HA, was dissolved in water to form a 100ml sol in volumetric flask.
25 ml sample of sol reacted with 12.1 ml of 0.1M NaOH. Find molar mass of acid.
Mass bottle 1.737 ± 0.001 g
Mass bottle + acid, HA
2.412 ± 0.001 g
Mass acid = ( 2.412 – 1.737) ± 0.002 = (0.675 ±0.002) g
% uncertainty = (0.002) x 100% = 0.3% 0.675
NaOH + HA → NaA + H2O
NaOH + HA → NaA + H2O M = 0.1M M = ?V = 12.1 ml V = 25 ml
MMM
VMVM
a
a
aa
bb
0484.011
251.121.011
? HA100 ml water added
25 ml transfer
NaOH M = 0.1MV = 12.1 ml
HA M = ?
Amt acid in 1000 ml = 4.84 x 10-2 molAmt acid in 100 ml = 4.84 x 10 -3 mol
1391084.4675.0
).(
3
r
r
M
MgMassMole
Cations/Metals/+ve ions
Gp 1 Gp 2 Gp 3 Transition metals ions ( variable oxidation states)
Oxidation state+1
Oxidation
state+2
Oxidation
state+3
Sc+3
Ti+2+3
V+2+3
Cr+2+3+6
Mn+2+3+6+7
Fe+2+3
Co+2+3
Ni+2
Cu+1+2
Zn+2
Li 1+ Be2+ Sc 3+ Ti 2+
Ti 3+V 2+
V 3+Cr 2+
C r3+
Cr6+
Mn 2+
Mn 3+
Mn 6+
Mn 7+
Fe 2+
Fe 3+
Co2+
Co 3+Ni2+ Cu1+
Cu2+Zn2+
Na 1+ Mg2+ Al 3+
K 1+ Ca2+
Anion/Non metal
Gp 5 Gp 6 Gp 7
Oxidation
state
Oxidation
state
Oxidation
state
-3 -2 -1
N3- O2- F-1
P3- S2- CI-1
Br-1
I-1
Ionic Compound
Li2O MgCI2 Al2O3 FeOIron(II) oxide
NiONickel(II)
oxide
CuOCopper(II) oxide
Li3N Mg3N2 AlN Fe3N2
Iron(II) nitride
Ni3N2
Nickel(II) nitride
Cu3N2
Copper(II) nitride
Oxidation state/Charge ion→ Li1+ O2-
Formula compound Li2 O1
Video on polyatomic ions
Writing Chemical Formula
Step 1 : Write Oxidation state/charge
Step 2 : Balance it, (electrically neutral) by cross multiply – as subscript
Metal/Cations/+ve ionNon Metal/
Anion/-ve ion
Polyatomic ionsGroup of non-metals bonded
together
Oxidation state
Oxidation state
Oxidation state
-1/+1 -2 -3
(OH)-1
Hydroxide(SO4)2-
Sulphate(PO4)3-
Phosphate
(CN)-1
Cyanide(SO3)2-
Sulphite
(SCN)-1
Thiocyanate
(CO3)2-
Carbonate
(NO3)-1
Nitrate(S2O3)2-
Thiosulphate
(NO2)-1
Nitrite(Cr2O7)2-
Dichromate
(NH4)+1
AmmoniumLi2(CO3) Mg(CO3) Al2(CO3)3 Fe(CO3) Ni(CO3) Cu(CO3)
Li(OH) Mg(OH)2 Al(OH)3 Fe(OH)2 Ni(OH)2 Cu(OH)2
Li2(SO4) Mg(SO4) Al2(SO4)3 FeSO4 Ni(SO4) Cu(SO4) Video on polyatomic ions
Ionic Compound
Cations/Metals/+ve ions
Gp1 Gp 2 Gp3 Transition metals ions ( variable oxidation states)
Oxidation state+1
Oxidation
state+2
Oxidation
state+3
Sc+3
Ti+2+3
V+2+3
Cr+2+3+6
Mn+2+3+6+7
Fe+2+3
Co+2+3
Ni+2
Cu+1+2
Li 1+ Be2+ Sc 3+ Ti 2+
Ti 3+V 2+
V 3+Cr 2+
C r3+
Cr6+
Mn 2+
Mn 3+
Mn 6+
Mn 7+
Fe 2+
Fe 3+
Co2+
Co3+Ni2+ Cu1+
Cu2+
Na 1+ Mg2+ Al 3+
K 1+ Ca2+
Oxidation state/Charge ion → Li1+ (CO3)2-
Formula compound Li2 (CO3)1
Step 1 : Write Oxidation state/charge ion
Step 2 : Balance it, (electrically neutral) by cross multiply – as subscript
Writing Chemical Formula
Metal/Cations/+ve ion Polyatomic ions
Acids AlkaliMetal Hydroxide
Metal oxides Salts Gas
HCIHydrochloric acid
KOHPotassium hydroxide
CuOCopper(II) oxide
CaCO3
Calcium carbonate
COCarbon monoxide
HNO3
Nitric acidNaOH
Sodium hydroxideMgO
Magnesium oxideNa2CO3
Sodium carbonate
CO2
Carbon dioxide
H2SO3
Sulphurous acidCa(OH)2
Calcium HydroxideZnO
Zinc oxideNaHCO3
Sodium bicarbonate
SO2
Sulphur dioxide
HCOOHMethanoic acid
NH3
AmmoniaNa2O
Sodium oxideKNO3
Potassium nitrateSO3
Sulphur trioxide
CH3COOHEthanoic acid
Mg(OH)2
Magnesium hydroxide
Al2O3
Aluminium oxidePb(NO3)2
Lead (II) NitrateNO2
Nitrogen dioxide
H3PO4
Phosphoric acidCu(OH)2
Copper (II) hydroxide
Fe2O3
Iron(III) oxideNaNO3
Sodium nitrateCH4
Methane
H2CO3
Carbonic acidAl(OH)3
Aluminium hydroxide
K2SPotassium sulphide
PbI2
Lead (II) nitrateH2S
Hydrogen sulphide
HNO2
Nitrous acidFe(OH)2
Iron (II) hydroxidePbS
Lead(II) sulphideAgCI
Silver chlorideO2
Oxygen
HFHydrofluoric acid
Fe(OH)3
Iron (III) hydroxideZnS
Zinc sulphideMgSO4
Magnesium sulphate
N2
Nitrogen
HCIOHypochlorous acid
Zn(OH)2
Zinc hydroxideAI2S3
Aluminium sulphide
Na2S2O3
Sodium thiosulphate
CI2
Chlorine
Chemical Formula for common chemicals
Naming chemical compound
Writing chemical formula
Writing chemical formula
VIDEO TUTORIALS
Chemical Eqn
1Pb(NO3)2(aq) + 2NaCI(aq) → 1PbCI2(s) + 2NaNO3(aq)
1Pb2+(aq) + 2NO3
-(aq) + 2Na+
(aq) + 2CI-(aq) → 1PbCI2(s) + 2Na+
(aq) + 2NO3
-(aq)
unchanged
1Pb2+(aq) + 2CI-
(aq) → 1PbCI2(s)
1Pb2+(aq) + 2NO3
-(aq) + 2Na+
(aq) + 2CI-(aq) → 1PbCI2(s )+ 2Na+
(aq) + 2NO3-(aq)
Break aq → ions
Cancel outCancel outSpectators ions- don’t participate in rxnCancel out ions from both sides of eqn
Only ions involved in rxn
Net ionic eqnComplete ionic eqnMolecular eqn
Break down electrolytes, (aq) → ion
Leave sol, liq, gas unchanged
Molecular eqn
Complete ionic eqn
Net ionic eqn
Na2CO3(aq) + 2HNO3(aq) → 2NaNO3(aq) + H2O(l)
+ CO2(g)
2Na+(aq) + CO3
2-(aq) + 2H+
(aq) + 2NO3-(aq) → 2Na+
(aq) + 2NO3-(aq) +
H2O(l) + CO2 (g)
2Na+(aq) + CO3
2-(aq) + 2H+
(aq) + 2NO3-(aq) → 2Na+
(aq) + 2NO3-(aq) +
H2O(l) + CO2 (g)
CO32-
(aq) + 2H+(aq) →H2O(l) +
CO2(g)
Break aq → ions
Net ionic eqn
Complete ionic eqn
Molecular eqn
Cancel out
Chemical Eqn
Cancel out
Net ionic eqnComplete ionic eqnMolecular eqn
Molecular eqn
Complete ionic eqn
Net ionic eqn
Net ionic eqn
Complete ionic eqn
Molecular eqn
2 Na3PO4(aq) + 3CaCI2(aq) → 6NaCI(aq) + Ca3(PO4)2(s)
6Na+(aq) + 2PO4
3-(aq) + 3Ca2
(aq) + 6CI-(aq) → 6Na+
(aq) + 6CI-(aq) +
Ca3(PO4)2(s)
6Na+(aq) + 2PO4
3-(aq) + 3Ca2
(aq) + 6CI-(aq) → 6Na+
(aq) + 6CI-(aq) +
Ca3(PO4)2(s)
2PO43-
(aq) + 3Ca2+(aq) →
Ca3(PO4)2(s)
Zn(s) + CuSO4(aq) → ZnSO4(aq) + Cu(s)
Zn(s) + Cu2+(aq) + SO4
2-(aq) → Zn2+
(aq) + SO42-
(aq) + Cu(s)
Zn(s) + Cu2+(aq) + SO4
2- (aq) → Zn2+
(aq) + SO42-
(aq)
+ Cu(s)
Zn (s) + Cu2+(aq) → Zn2+
(aq) + Cu(s)
Cancel out
SO42-
(aq) + Ba2+(aq) → BaSO4 (s)
2K+(aq) + SO4
2-(aq) + Ba2+
(aq) + 2Cl-(aq) → BaSO4(s) + 2K+
(aq) + 2Cl-(aq)
2K+(aq) + SO4
2-(aq) + Ba2+
(aq) + 2Cl-(aq) →BaSO4(s) + 2K+
(aq) + 2Cl-(aq)
Mg(s) + 2H+(aq) +2Cl-
(aq) → Mg2+(aq) + 2Cl-
(aq)
+ H2(g)
Mg(s) + 2H+(aq) + 2Cl-
(aq) → Mg2+(aq) + 2Cl-
(aq) +H2(g)
Cancel out
Chemical Eqn
Cancel out
Net ionic eqnComplete ionic eqnMolecular eqn
Molecular eqn
Complete ionic eqn
Net ionic eqn
Net ionic eqn
Complete ionic eqn
Molecular eqn
Mg(s) + 2HCl(aq) → MgCl2(aq) + H2(g)
Mg(s) + 2H+(aq) → Mg2+
(aq) + H2(g)
K2SO4(aq) + BaCl2 (aq) → BaSO4(s) + 2KCl(aq)
3CO32-
(aq) + 2Al3+(aq) →
Al2(CO3)3(s)
6NH4+
(aq) + 3CO32-
(aq) + 2Al3+(aq) + 6NO3
-(aq) → 6NH4
+(aq) + 6NO3
-(aq) +
Al2(CO3)3(s)
6NH4+
(aq) + 3CO32-
(aq) + 2Al3+(aq) + 6NO3
-(aq) → 6NH4
+(aq) + 6NO3
-(aq) +
Al2(CO3)3(s)
OH-(aq) + H+
(aq) → H2O(l)
2Na+(aq) + 2OH-
(aq) + 2H+(aq) + SO4
2-(aq) → 2Na+
(aq) + SO42-
(aq) + 2H2O(l)
2Na+(aq) + 2OH-
(aq) + 2H+(aq) + SO4
2-(aq) → 2Na+
(aq) + SO42-
(aq) + 2H2O(l)
Cancel out
Chemical Eqn
Cancel out
Net ionic eqnComplete ionic eqnMolecular eqn
Molecular eqn
Complete ionic eqn
Net ionic eqn
Net ionic eqn
Complete ionic eqn
Molecular eqn
2NaOH(aq) + H2SO4 (aq) → Na2SO4(aq) + 2H2O(l)
3(NH4)2CO3(aq) + 2Al(NO3)3(aq) → 6NH4NO3(aq) + Al2(CO3)3(s)
Ca2+(aq) + CO3
2-(aq) → CaCO3 (s)
Ca2+(aq)+ 2Cl- (aq) + 2Na+
(aq)+ CO32- (aq)→ 2Na+
(aq) + 2Cl-(aq) +
CaCO3 (s)
Ca2+(aq)+ 2Cl-
(aq) + 2Na+(aq)+ CO3
2-(aq) → 2Na+
(aq) + 2Cl-(aq) +
CaCO3 (s)
OH-(aq) + H+
(aq) → H2O(l)
2Na+(aq) + 2OH-
(aq) + 2H+(aq) + SO4
2-(aq) → 2Na+
(aq) + SO42-
(aq) + 2H2O(l)
2Na+(aq) + 2OH-
(aq) + 2H+(aq) + SO4
2-(aq) → 2Na+
(aq) + SO42-
(aq) + 2H2O(l)
Cancel out
Chemical Eqn
Cancel out
Net ionic eqnComplete ionic eqnMolecular eqn
Molecular eqn
Complete ionic eqn
Net ionic eqn
Net ionic eqn
Complete ionic eqn
Molecular eqn
2NaOH(aq) + H2SO4 (aq) → Na2SO4(aq) + 2H2O(l)
CaCl2 (aq) + Na2CO3(aq) → 2 NaCl(aq) + CaCO3(s)
4 g H2 508 g I2
512 g HI 150 g NO2
300 g N2O4
Simulation conservation mass/balancing eqn
Click to view animation
+2 moles H2 2 moles I2 4 moles HI
150 g NO2
3 moles NO23 moles NO2 3 moles N2O4+ +
3NO2 + 3NO2 → 3N2O4 2H2 + 2I2 → 4HI
= +
Video on stoichiometry
=
Concept Map
Chemical Rxn Chemical change Chemical eqn Balancing chemical eqn
Molecular Eqn
1Pb(NO3)2(s) + 2KI(aq) → 1PbI2(s) + 2KNO3 (aq)
1Pb2+(aq) + 2NO3
-(aq) + 2K+
(aq) + 2I-(aq) → 1PbI2(s) + 2K+
(aq)
+ 2NO3-(aq)
1Pb2+(aq) + 2CI-
(aq) → 1PbCI2(s)
Coefficient Mole ratio (reactant) →
(product) 1 : 2 → 1
: 2
Complete ionic eqn
Net ionic eqn
Reaction StoichiometryQuantitative relationship bet quantities react/
prodFind quantities/amt (mass, mole, vol)
Predicts how much react and amt prod formChemical rxn react in definite ratio
Exercise
Write balanced eqn for following rxn1. Rxn of sulphur dioxide and oxygen to form sulphur trioxide2SO2(g) + O2(g) → 2SO3(g)
2. Neutralization bet potassium hydroxide and sulphuric acid to form potassium sulphate and water2KOH(aq) + H2SO4(aq) → K2SO4(aq) + 2H2O(I)
3. Combustion of ethane (C2H6) to form carbon dioxide and water 2C2H6(g) + 7O2(g ) → 4CO2(g) + 6H2O(I)
4. Displacement rxn bet zinc metal and copper(II) sulphate sol to form copper metal and zinc sulphate Zn(s) + CuSO4(aq) → Cu(s) + ZnSO4(aq)
5. Decomposition of zinc carbonate to form zinc oxide and carbon dioxide when heated ZnCO3(s) → ZnO(s) + CO2(g)
6. Ammonia react with oxygen to form nitrogen monoxide and water. 4NH3(g) + 5O2(g) → 4NO(g) + 6H2O(I)
• Manganese(IV) oxide react with hydrochloric acid to form manganese(II) chloride sol, chlorine and water MnO2(s) + 4HCI(aq) → MnCI2(aq) + CI2(g) + 2H2O(I)
•Neutralization bet aq ammonia with hydrochloric acid to form ammonium chloride and water. NH4OH(aq) + HCI(aq) → NH4CI(aq) + H2O(I)
Acknowledgements
Thanks to source of pictures and video used in this presentation
Thanks to Creative Commons for excellent contribution on licenseshttp://creativecommons.org/licenses/
Prepared by Lawrence Kok
Check out more video tutorials from my site and hope you enjoy this tutorialhttp://lawrencekok.blogspot.com