Conservation of mass
1
When carbon burns it combines with oxygen to form carbon dioxide. The diagram shows some carbon atoms
reacting with some oxygen molecules.
a
2
Finish the diagram by drawing the correct number of carbon dioxide molecules. One has been done for
you.
b
Write ‘reactants’ and ‘products’ under the correct sides of the diagram.
c
12 g of carbon reacted with 32 g of oxygen. What mass of carbon dioxide was formed? Circle the correct
answer.
12 g 24 g 32 g 44 g 64 g
This diagram below shows the reaction between marble chips and acid.
This is the word equation for the reaction:
calcium
carbonate
+
hydrochloric
acid

calcium
chloride
+
carbon
dioxide
+
water
a
Is carbon dioxide a solid, a liquid or a gas? ____________________________________
b
What would you expect the balance to read when the reaction has finished? Circle the correct answer.
179 g
c
180 g
181 g
Explain your answer to part b. _____________________________________________
______________________________________________________________________
3
If you heat a piece of copper, it combines with oxygen from the air to form a black layer of
copper oxide.
a
Write a word equation for this reaction.
______________________________________________________________________
b
How would the mass of your piece of copper change as you heated it?
______________________________________________________________________
c
Why would this happen? _________________________________________________
______________________________________________________________________