1. Exercise 1 – identifying reactants and products
Question
Reactants
Products a)
Iron + oxygen
iron oxide b)
Sodium + water
Sodium hydroxide + hydrogen c)
Calcium carbonate
calcium oxide + carbon dioxide d)
Ammonia + oxygen
nitrogen + water e)
Carbon dioxide + water
Glucose + oxygen f)
Copper carbonate + sulphuric acid
Copper sulphate + water + carbon dioxide

2. Exercise 2 – describing what happens in a word equation
Iron reacts with sulphur to make iron sulphide.
Magnesium reacts with oxygen to make magnesium oxide.
Calcium oxide reacts with water to make calcium hydroxide.
Ethane reacts with water to make ethanol.
Propane reacts with oxygen to make carbon monoxide and water.
Copper carbonate creates copper oxide and carbon dioxide.

3. Exercise 3 – what to put into an equation and what not to put in a word equation (writing word equations from descriptions)
Sodium hydroxide + hydrochloric acid  Sodium chloride + water
Magnesium + oxygen  Magnesium oxide
Carbon + oxygen  carbon dioxide
Lead nitrate + sodium chloride  Lead chloride + sodium nitrate
Octane  Propane + pentane
Sodium + water  Sodium hydroxide + hydrogen

4. Exercise 4 – identifying whether reactions happen or not
There IS a reaction
There is NOT a reaction

5. Exercise 5 – name the substances from their formulae
Iron oxide
Sodium bromide
Sodium oxide
Hydrogen oxide (aka water)
Calcium carbonate
Hydrogen nitrate

6. Exercise 6 – identify state symbols in a symbol equation
Solid
Dissolved in water
Gas
Liquid

7. Exercise 7 – work out the number of elements in a formula
2 oxygens
1 neon
2 hydrogens, 2 oxygens
2 carbons, 6 hydrogens, 1 oxygen
2 potassium, 1 carbon, 3 oxygens
6 carbons, 12 hydrogens, 6 oxygens
1 calcium, 2 oxygens, 2 hydrogens
1 calcium, 2 nitrogens, 6 oxygens

8. Exercise 8 – work out the formula of a substance from its particle diagramCO
Fe2O3
Na2CO3
C4H10
NaCl
H2O

9. Exercise 9 – write an equation using particle diagrams (little numbers only)
C4H10  C2H4 + C2H6
C + O2  CO2
FeCO3  FeO + CO2

10. Exercise 10 – write an equation using particle diagrams (little numbers and big numbers)
C + CO2  2CO
Fe2O3 + 3CO  2Fe + 3CO2
CH4 + 2O2  CO2 + 2H2O
Na2CO3 + 2HCl  2NaCl + CO2 + H2O
2Fe2O3 + 3C  4Fe + 3CO2

11. Exercise 11 – Work out the number of elements in symbol equations (little numbers only)
Question
Number of elements a)
1 carbon and 2 oxygens b)
1 calcium and 2 chlorines c)
1 iron and 1 sulphur d)
1 sodium, 2 hydrogens, 1 oxygen, 1 chlorine e)
1 iron, 1 sulphur, 4 oxygens, 1 calcium f)
1 calcium, 1 carbon, 3 oxygens

12. Exercise 12 – Work out the numbers of elements in symbol equations (big and little numbers)
Question
Number of elements a)
2 aluminiums b)
2 hydrogens, 2 chlorines c)
4 hydrogens, 2 oxygens d)
10 oxygens e)
3 carbons, 6 oxygens f)
2 nitrogens, 6 hydrogens

13. Exercise 13 – Work out if symbol equations are balanced or not balanced

14. Exercise 14 – Balance symbol equations (gaps put in for you)
a) CO2 + C  ­2CO b) 2Fe + O2  2FeO c) 2HCl + Ca(OH)2  2H2O + CaCl2 d) 2Na + O2  2Na2O e) C3H8 + 5O2  3CO2 + 4H2O f) 2Na + 2H2O  2NaOH + H2

15. Exercise 15 – Spot the mistake with these equations
They put a small 2 next to the O.
Correct answer = 2Ca + O2  2CaO
b) They changed the small numbers for O2 and H2O
Correct answer = CH4 + 2O2  CO2 + 2H2O
c) They put a small 2 next to the O.
Correct answer = 2C + O2  2CO

16. Exercise 15 – Spot the mistake with these equations
d) They took the 2 away from H2 Correct answer = 2K + 2H2O  2KOH + H2 e) They put a big 8 between the Fe and the S Correct answer = 8Fe + S8  8FeS f) They put a big 2 between the Fe and the 2 Correct answer = 2Fe + O2  2FeO

17. Exercise 16 – Using online help

18. Exercise 17 – Balance symbol equations with no help
2Mg + O2  2MgO
2H2 + O2  2H2O
2Na + Cl2  2NaCl
2C + O2  2CO
Fe2O3 + 3CO  2Fe + 3CO2
C6H12O6 + 6O2  6CO2 + 6H2O

19. Exercise 18 – identifying substances that are oxidised or reduced by looking at a balanced equation (using oxygen)
Mg + FeO  MgO + Fe
Magnesium was oxidised and iron was reduced.
b) CO2 + C  2CO
Carbon was oxidised and carbon dioxide was reduced.
c) Fe2O3 + 3CO  2Fe + 3CO2
Carbon monoxide was oxidised and iron was reduced.

20. Exercise 19 – balancing charges in equations (ionic equations)
Balanced
Not balanced
Na2CO3(s) + Ca+(aq)  2Na+ + CaCO3(s)

21. Exercise 20 – identifying substances in ionic equations that are oxidised and reduced using electrons.
Cu2+ + Mg  Mg2+ + Cu
The copper is being reduced and the magnesium is being oxidised.
b) Cl2 + 2Fe2+  2Cl- + 2Fe3+
The chlorine is being reduced and the iron is being oxidised.
c) 2H+ + O2-  H2O
The hydrogen is being reduced and the oxygen is being oxidised.

22. Exercise 21 – balancing equations with electrons (half equations)
K+ + e-  K balanced
2F-  F2 + 2e-
Mg2+ + 2e-Mg
2S2-  S2 + 4e-
2H+ +2e-  H2
2Br-  Br2 + 2e-
4OH-  2H2O + 2O2 + 4e-