Acid–alkali indicators

2 marks · Easy

Table 1 shows the colour changes of three common indicators in different solutions.

(a)

Complete the table by giving the colour of litmus in alkali and phenolphthalein in acid.

[2 marks]

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(a) — · must show Litmus blue in alkali, Phenolphthalein colourless in acid

Must show: Litmus: blue/alkali, Phenolphthalein: colourless/acid

Also accept: colorless

Common mistakes: pink for phenolphthalein in acid; red for litmus in alkali

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Marking points

B1 (a) · 1 mark · Litmus is blue in alkali.

B2 (a) · 1 mark · Phenolphthalein is colourless in acid.

Worked solution