The reactivity series SA - (CCEA)

• The reactivity series is a list that shows the order of reactivity of metals.

• The metals are ordered by comparing the observations of their reactions with oxygen, water and steam.

The reactivity series is a list that shows the order of reactivity of some common metals.

In general, the more reactive a metal is, the more vigorously it reacts with other substances.

Key fact

You will need to learn the order of these metals.

A mnemonic can help: ‘Poor Scientists Can Make A Zoo In Class’.

We can examine the reactivity of metals by observing their reactions with water, steam and acid.

This table summarises the reactions of some metals in the reactivity series.

Please use the link below to access the article on: Prescribed practical (C2) - Investigate the reactivity of metals

(https://www.bbc.co.uk/bitesize/articles/zsw746f)

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

metal + water → metal hydroxide + hydrogen

For example:

Sodium reacts vigorously with water.

sodium + water ➞ sodium hydroxide + hydrogen

2Na(s) + 2H₂O(l) ➞ 2NaOH(aq) + H₂(g)

Calcium reacts readily with water.

calcium + water ➞ calcium hydroxide + hydrogen

Ca(s) + 2H₂O(l) ➞ Ca(OH)₂(aq) + H₂(g)

Calcium hydroxide is slightly soluble in water so once the solution is saturated, it starts to become milky as solid calcium hydroxide appear.

The apparatus below is used to react calcium with water and collect the gas.

This would not be used with sodium or potassium as they float and the reaction is too vigorous

Some metals that do not react with water can be reacted with steam due to the increased temperature of the reaction.

Magnesium reacts very slowly with water.

However, it reacts vigorously with steam:

magnesium + steam → magnesium oxide + hydrogen

Mg(s) + H₂O(g) → MgO(s) + H₂(g)

Metals which react with steam form the solid metal oxide and hydrogen gas.

In general, the more reactive the metal, the more rapid the reaction.

Aluminium is unusual, because it is a reactive metal that does not react with water.

Its surface forms a protective layer of aluminium oxide that keeps water away from the metal below.

The apparatus used to react a metal with steam and collect the gas produced is shown below.

When metals react with acid hydrogen gas is produced.

The general equation is:

Metal + Acid → Salt + Hydrogen

For example, when magnesium reacts with hydrochloric acid, the salt magnesium chloride is formed along with hydrogen gas.

During the reaction the following observations would be made:

• bubbles of colourless gas;
• exothermic (heat given out);
• the silver solid (magnesium) would disappear;
• a colourless solution forms.

It is not safe to react the most reactive metals (potassium and sodium) with acid in a lab.

As you move down the reactivity series (aluminium, zinc, iron) the metals are less reactive, so less bubbles would be observed, less heat given out and they would take longer to fully react.

Copper does not react with acid.