Chemistry 0620 · IGCSE · Carboxylic acids

Carboxylic acids — practice question

Citric acid occurs in lemon juice, and it displays the usual properties of an acid.
(a)[2]

Describe how you could use Universal Indicator to find the pH of a lemon juice solution.

(b(i))[1]

Draw a ring around a carboxylic acid functional group on the diagram.

(b(ii))[1]

State the name of one additional carboxylic acid.

(c(i))[2]

Fill in the missing products in the word equation for this reaction.\n\ncitric acid + calcium carbonate $\rightarrow$ calcium citrate + [BLANK] + [BLANK]

(c(ii))[1]

Suggest a method for separating the excess calcium carbonate from the remaining solution.

(d)[1]

Would you describe this reaction as exothermic or endothermic? Give a reason for your answer.

(e(i))[2]

Fill in the missing parts of the chemical equation for the fermentation of glucose to produce ethanol.\n\n$\text{C}_6\text{H}_{12}\text{O}_6 \rightarrow \ldots\text{C}_2\text{H}_5\text{OH} + \ldots\text{CO}_2$

(e(ii))[2]

State two conditions that fermentation requires.

(e(iii))[2]

Complete the table shown below and work out the relative molecular mass of glucose.

Worked solution & mark scheme

This 14-mark question has a full step-by-step worked solution and mark scheme. One marking point: Introduce universal indicator to the lemon juice/solution

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