Writing word equations and interpreting symbol equations. A Word equation
Word equations summarise chemical reactions. They show the reactants and products.
Write word equations for the reactions below.
1 Copper reacts with oxygen to make copper oxide.
+ →
2 Potassium reacts with water to make hydrogen and potassium hydroxide.
+ → +
3 Magnesium reacts with hydrochloric acid to make magnesium chloride and hydrogen.
+ → +
4 Zinc reacts with iron oxide to make iron and zinc oxide.

5 Iron oxide and carbon react together to make iron and carbon dioxide.

6 Magnesium displaces copper from copper sulfate to make magnesium sulfate and copper.

B Symbol equations
A balanced symbol equation tells us more than a word equation. It shows
• The formulae of reactants (starting substances) and products (substances that are made in the
reaction)
• How the atoms are rearranged in a reaction
• The relative amounts of reactants and products
Answer the questions below for this equation: 2CuO + C → 2Cu + CO 2
1 Give the formulae of the two reactants, copper oxide and carbon.
and
2 Give the formula of a carbon dioxide molecule.
3 Give the number of oxygen atoms in one carbon dioxide molecule.
4 Give the total number of atoms in one carbon dioxide molecule.
5 Before the reaction starts, oxygen atoms are joined to copper. What are the oxygen atoms joined to
when the reaction has finished?
6 How many carbon atoms are shown on each side of the equation?
7 How many copper atoms are shown on each side of the equation?