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Question 1

A scientist works in a lab that tests samples of vinegar.

Vinegar is mainly a mixture of ethanoic acid and water.

a)

Vinegar needs to have a minimum of 5% acidity in order to be used to preserve food.

Calculate how much ethanoic acid needs to be in 25 cm3 of vinegar in order for it to be used to preserve food.

Use the equation:

percentage acidity = mass of vinegar (g)mass of ethanoic acid (g)× 100

Note that the mass of 1 cm3 of vinegar is 1.01 g.

(0/2 marks)

b)

The scientist uses a titration to find out how much 1 mol/dm3 sodium hydroxide she needs to add to exactly react with 25.0 cm3 of vinegar.

The equation below shows ethanoic acid behaving as an acid.

CH3COOH ⇌ CH3COO + H+

Calculate the minimum volume of sodium hydroxide the scientist uses in her titration.

The relative formula mass of CH3COOH is 60.0.

(0/5 marks)

0

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