The Reactivity Series: Answers

 

 Write word and symbol equations for the reactions between:

  • Zinc and hydrochloric acid

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Remember that a metal reacting with an acid forms a salt and hydrogen.

  • Magnesium and sulfuric acid

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  • Calcium and water

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Remember that a metal reacting with water forms a metal hydroxide and hydrogen.

What would happen if you added zinc to a solution of magnesium sulfate?

Zinc is below magnesium in the reactivity series which means it can’t take the place of magnesium in its compound (displacement). No reaction would happen.

In the reaction between sodium and copper nitrate, state which element is i) oxidised, ii) reduced, iii) the oxidising agent and iv) the reducing agent.

When sodium reacts with copper nitrate, sodium displaces copper to form copper and sodium nitrate. Sodium has turned from a neutral element to a positive ion (Na+) so it has lost electrons. Copper has gone from a positive ion (Cu2+) to a neutral element by gaining electrons. This means the sodium is oxidised and the copper is reduced (OILRIG). Therefore, sodium is the reducing agent while copper is the oxidising agent.

How is rust formed and how can it be prevented from occurring?

Rust is the name given to hydrated iron oxide. It is formed when iron reacts with oxygen in air or water. Rust can be prevented using a protective barrier to prevent contact with air or water (such as a layer of paint, plastic, oil or grease). Another method involves galvanising the iron by covering it with a layer of zinc. The zinc is more reactive than iron and acts as a sacrificial metal, reacting more readily with oxygen so that the zinc becomes oxidised instead of the iron.