Chemistry 0620 · IGCSE · Separation and purification

Separation and purification — practice question

A liquid used for cleaning metal contains the following compounds: ethanoic acid, ethanol, glycerol, sodium chloride and water.
(a(i))[1]

Draw the structure of the functional group that is found in ethanoic acid.

(a(ii))[1]

Which one of these pH values is acidic? Circle the right answer: pH4, pH7, pH9, pH13.

(a(iii))[1]

What kind of reaction is shown here? Circle the correct option: neutralisation, oxidation, polymerisation, reduction.

(a(iv))[1]

What is the meaning of the word exothermic?

(b)[1]

Deduce the molecular formula of glycerol by showing the numbers of carbon, hydrogen and oxygen atoms present.

(c)[2]

Balance the equation for the incomplete combustion of ethanol. $\text{C}_2\text{H}_5\text{OH} + 2\text{O}_2 \rightarrow \ldots\ldots\ldots\text{CO} + \ldots\ldots\ldots\text{H}_2\text{O}$

(d(i))[3]

Describe a way to obtain pure samples of both sodium chloride and water from aqueous sodium chloride. Explain why this method is successful.

(d(ii))[1]

Which physical property could be measured to tell whether a water sample is pure?

(d(iii))[2]

Describe how to test for chloride ions. Include both the test and the result.

Worked solution & mark scheme

This 13-mark question has a full step-by-step worked solution and mark scheme. One marking point: The functional group is shown as -COOH / -CO2H or as a correct displayed formula

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