Metals with acids and salt solutions: the reactivity series

Metals with dilute acids

A metal that is above hydrogen in the reactivity series reacts with a dilute acid, and it gives hydrogen gas and a salt.

Equal pieces of magnesium, aluminium, zinc and iron are put in dilute hydrochloric acid in four test tubes. The reaction is fastest with magnesium, and gets slower in the order aluminium, zinc, iron. Copper does not react.

The test tube with magnesium gets warm, and the one with copper does not change. Nitric acid is different: it is a strong oxidising agent, and it does not give hydrogen with most metals.

You should find that after enough time all three give the same volume, because the amounts of metal are equal.

Metals with salt solutions: displacement

A more reactive metal displaces a less reactive metal from its salt solution.

Copper does not displace iron from iron sulphate, because it is less reactive.

The reactivity series

If we put together what we find about the reactions with oxygen, water, acids and salt solutions, we get a list, from the most reactive metal to the least reactive. This is the reactivity series.

Hydrogen is put in the list, although it is not a metal, as a mark for the metals that give hydrogen with acids.

Using the series

1. Reactions with water and acids: only the metals above hydrogen give hydrogen with dilute acids.
2. Displacement: a metal displaces the metals that are below it from their salt solutions.
3. Extraction: the position in the series decides how a metal is got from its ore (the last lesson of this chapter).
4. Choice of metals: silver, gold and platinum are at the bottom, which is why they stay shiny and are used in jewellery.

Practise with new numbers

Try it in Python

This program predicts how metals react with cold water, steam and dilute acid from their place in the series.

Remember these

• Metals above hydrogen give hydrogen with dilute acids. Copper, silver and gold do not.
• A more reactive metal displaces a less reactive metal from its salt solution.
• The series: K, Na, Ca, Mg, Al, Zn, Fe, Pb, (H), Cu, Hg, Ag, Au.

Check yourself

Try each one on your own first. If you are stuck, open a hint. Then check with Show the answer.

1. Does zinc displace iron from iron sulphate solution?

2. Which reacts faster with dilute acid, magnesium or iron?

3. A copper wire is left in silver nitrate solution. What do you see?

4. Why are gold and silver used for jewellery?