Question

You are given samples of three metals - sodium, magnesium and copper. Suggest any two activities to arrange them in order of their decreasing reactivities.

Answer 1

Sodium, magnesium and copper can be arranged based on their reactivity with water.

1. Sodium reacts violently with cold water because it is the most reactive of the three.
2. Magnesium does react with hot water to form magnesium hydroxide and hydrogen gas. It reacts with steam even more vigorously to form magnesium oxide.
3. Copper does not react even with steam, and it is the least reactive of the three.

Sodium, magnesium and copper can be arranged based on their reactivity with a dilute acid as well.

1. Sodium reacts with dilute hydrochloric acid violently.
2. Magnesium reacts with dilute hydrochloric acid but less rapidly than sodium.
3. Copper is the least reactive, and it does not react with dilute hydrochloric acid.

So the order of their decreasing reactivity is sodium > magnesium > copper.