Summary The exam style practice questions with answers based on the new IGCSE specification for Cambridge International students.

Stoichiometry and Mole Concept
Calculations
for IGCSE Chemistry
With answers




The booklet is based on the Cambridge IGCSE chemistry specification from
2023
This booklet covers the following topics
1 . writing Formulae , word equation, symbol equation and ionic equations
2.Calculating relative formula mass(molar mass) and percentage by mass
3.Calculating moles, molecules , atoms and mass of chemical compound
4.Calculating the moles and volume of gases
5.Calculating the concentration , moles and volume of solutions
6. Calculating the moles, molecules and atoms ( calculations with Avogadro
Constant)
7.Calculating empirical formula and molecular formula.
8. Percentage purity and percentage yield
9. Calculating of reacting masses , excess and limiting reagents and prediction of
the quantity of reactants and masses
10.Calculations problems related with titrations
11. Answers

,Formulae , word equation, symbol equation
and ionic equations
Writing chemical formulae
(1) What names would you give these compounds?

a) NaI ……………………………………………
b) MgS ……………………………………………
c) Li2O ……………………………………………
d) Li3N ……………………………………………
e) Ca(OH)2………………………………………...
f) Fe3 (PO4 ) ……………………………………...
g) KBr…………………………………………….
h) HNO3………………………………………......
i) Al(OH)3……………………………………...
j) SiCl4 ………………………………………….
k) CuCO3 ……………………………………….
l) FeSO4 ………………………………………..
m) Mg3N2 ……………………………………..
n) C6H14 ……………………………………….
o) PCl3 …………………………………………
p) K2Cr2O7 …………………………………….
q) KNO2 ……………………………………….
r ) Al2(SO3)3…………………………………

(2) Use your Periodic Table to help you give the formula of these compounds:

a) copper nitrite …………………………………
b) Carbon sulfide……………………………………
c) Phosphorus chloride ……………………………..
d) Silicon oxide……………………………………...
e) Magnesium nitride ……………………………….
f) Lithium hydride…………………….. ……………
g) Potassium sulfate………………………………….
h) Aluminium fluoride…………………………………
i) Iron(III) oxide…………………………………….
j) Calcium nitrate…………………………………..
k) Zinc chloride…………………………………...
l) Ammonia……………………………………….
m) Cobalt (II) chloride …………………………...
n) Copper(II) sulfate…………………………….
o) Ammonium phosphate…………………………
p) Carbon tetrachloride………………………..

(3) How many atoms of the different elements are there in the formulae of these compounds?

i) Sodium hydroxide, Na3 PO4…………………………………………………………………………...
ii) Proponoic acid , C2H5COOH………………………………………………………………………..
iii) Auminium sulfate Al2(SO4)3………………………………………………………………………………..
iv) Copper nitrate, Cu(NO3)2………………………………………………………………………….....
v) Sucrose (sugar), C12H22O11………………………………………………………………………..

, Writing word chemical equations, formula ( symbol)
chemical equations , balancing chemical equations and ionic
equations
(1) Write word equations for the reactions described below.

a) Iron rusts because it reacts with oxygen in the air to form a compound called iron(III) oxide.
………………………………………………………………………………………………………………..
b) Sodium hydroxide neutralises sulfuric acid to form sodium sulfate and water.
………………………………………………………………………………………………………………...
c) Sodium reacts strongly with water to give a solution of sodium hydroxide; hydrogen gas is also given off.
…………………………………………………………………………………………………………………
d) Copper carbonates decomposes to copper(II) oxide and carbon dioxide.
……………………………………………………………………………………………………………………
e) Magnesium carbonate reacts with nitric acid to give magnesium nitrate , carbon dioxide and water.
…………………………………………………………………………………………………………………..

(2) Balance the following equations.

a) …Cu + O2 → …CuO
b) N2 + …H2 …NH3
c) …Na + O2 → …Na2O
d) …NaOH + H2SO4 → Na2SO4 + …H2O
e)…Al + …Cl2 → …AlCl3
f) …Fe + …H2O → …Fe3O4 + …H2
g) .... NO2 → N2 + ... O2
h) K2CO3 + ... HCl →... KCl + CO2 + H2O
i) ….. C3H8 + ... O2 → ... CO2 + 4H2O
j) Fe2O3 + ...CO → ...Fe + ...CO2

(3)Write word and balanced chemical equations for the reactions between:
a) Sodium and water
Word equation………………………………………………………………………………………………………………
Balanced chemical equation ……………………………………………………………………………………………………

b) Magnesium and steam
Word equation………………………………………………………………………………………………………………
Balanced chemical equation ……………………………………………………………………………………………………

c) Calcium and oxygen
Word equation………………………………………………………………………………………………………………
Balanced chemical equation ……………………………………………………………………………………………………

d) Bromine and potassium iodide solution
Word equation………………………………………………………………………………………………………………
Balanced chemical equation ……………………………………………………………………………………………………

e) Zinc and copper sulfate solution.
Word equation………………………………………………………………………………………………………………
Balanced chemical equation ……………………………………………………………………………………………………