Reactions of metals

Reaction of metals with water

When a metal reacts with water, a metal hydroxide and hydrogen are formed.

Group 1

Sodium reacts rapidly with cold water. The word equation is:

sodium + water → sodium hydroxide + hydrogen

The balanced chemical equation is:

2Na(s) + 2H2O(l) → 2NaOH(aq) + H2(g)

Group 2

The formulae of a group 1 metal hydroxide is different to a group 2 metal hydroxide. This affects the balancing of the chemical equations.

Calcium reacts more slowly with cold water. The word equation is:

calcium + water → calcium hydroxide + hydrogen

The balanced chemical equation is:

Ca(s) + 2H2O(l) → Ca(OH)2(aq) + H2(g)

Reaction of metals with dilute acids

When a metal reacts with a dilute acid, a salt and hydrogen are formed.

The more reactive the metal, the more rapid the reaction is. A metal below hydrogen in the reactivity series will not react with dilute acids.

For example, magnesium reacts rapidly with dilute hydrochloric acid:

magnesium + hydrochloric acid → magnesium chloride + hydrogen

Mg(s) + 2HCl(aq) → MgCl2(aq) + H2(g)

The salt magnesium chloride is dissolved in the water, so it has the state symbol (aq) meaning aqueous.

Here are some common acids, their formula and ions:

Name of acidFormulaIons
Hydrochloric acidHClH+ and Cl-
Sulfuric acidH2SO4H+ and SO42-
Nitric acidHNO3H+ and NO3-
Question

What is the name and formula of the salt formed when magnesium reacts with sulfuric acid?

Magnesium sulfate, MgSO4.

Question

Write the balanced chemical equation for the reaction of magnesium with sulfuric acid.

Mg(s) + H2SO4(aq) → MgSO4(aq) + H2(g)