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Redox of metals for OCR A-level Chemistry

Redox of metals

This page covers the following topics:

1. Oxidation of metals

Reactivity series can help determine if metals react with cold water, diluted acids or just oxygen. Reactive metals tend to form positive ions in many of these reactions. Unreactive metals are less likely to react with the aforementioned compounds to form positive ions.

The most reactive metals react with water to produce metal hydroxides and hydrogen. For example:
2K + 2Hโ‚‚O โ†’ 2KOH + Hโ‚‚

Some metals react with acids to displace hydrogen forming metal salts and hydrogen. For example:
Mg + 2HCl โ†’ MgClโ‚‚ + Hโ‚‚

During reactions with oxygen metals are oxidised to produce metal oxides. For example:
4Na + Oโ‚‚ โ†’ 2Naโ‚‚O

Oxidation of metals

1

Provide a balanced chemical equation for the reaction between lithium and water.

The most reactive metals react with water to produce metal hydroxides and hydrogen.

2Li + 2Hโ‚‚O โ†’ 2LiOH + Hโ‚‚

Provide a balanced chemical equation for the reaction between lithium and water.

2

Describe how the tendency to form positive ions change with a decreasing reactivity of metals.

Reactive metals tend to form positive ions in many of these reactions. Unreactive metals are less likely to react with the aforementioned compounds to form positive ions.

The tendency to form positive ions decrease with a decreasing reactivity of metals.

Describe how the tendency to form positive ions change with a decreasing reactivity of metals.

3

Name the product of a reaction between magnesium and oxygen.

During reactions with oxygen metals are oxidised to produce metal oxides.

magnesium oxide

Name the product of a reaction between magnesium and oxygen.

4

Provide a balanced chemical equation for the reaction between barium and water.

The most reactive metals react with water to produce metal hydroxides and hydrogen.

Ba + 2Hโ‚‚O โ†’ Ba(OH)โ‚‚ + Hโ‚‚

Provide a balanced chemical equation for the reaction between barium and water.

5

A piece of calcium is added to a diluted sulphuric acid solution. Provide a balanced chemical equation for the reaction between these two compounds.

Some metals react with acids to displace hydrogen forming metal salts and hydrogen.

Ca + Hโ‚‚SOโ‚„ โ†’ CaSOโ‚„ + Hโ‚‚

A piece of calcium is added to a diluted sulphuric acid solution. Provide a balanced chemical equation for the reaction between these two compounds.

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