Ethanol can be oxidised by heating with potassium dichromate(VI) in dilute sulfuric acid

2 marks · Easy

Ethanol can be oxidised by heating it with potassium dichromate(VI) in dilute sulfuric acid.

Calculate the number of different substances (including ethanol and all reagents used) that must be present in the test-tube for this reaction to occur, according to standard laboratory practice.

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Three different substances: ethanol, potassium dichromate(VI), and dilute sulfuric acid.

Also accept: 3 (ethanol, potassium dichromate(VI), dilute sulfuric acid); three (ethanol, potassium dichromate(VI), dilute sulfuric acid)

Common mistakes: Counting products such as ethanoic acid as required at the start; Omitting sulfuric acid or dichromate

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Marking points

M1 · 1 mark · Identifies ethanol and potassium dichromate(VI) as required substances.

A1 · 1 mark · Correctly includes dilute sulfuric acid to make a total of three substances needed.

Worked solution

The three substances needed in the test-tube are:

- Ethanol (the substance being oxidised)

- Potassium dichromate(VI) (the oxidising agent)

- Dilute sulfuric acid (provides acidic conditions for the reaction)

So, three substances must be present.