Edexcel IGCSE Chemistry 2.49 water test

Practise water-test questions by naming the reagent and giving the correct colour change for water in a liquid or product.

Exam points

State that anhydrous copper(II) sulfate turns from white to blue in water.
Use cobalt chloride only when the blue-to-pink colour change is matched correctly.

[Maximum number: 2]

A student uses this apparatus to investigate the decomposition of hydrogen peroxide solution.

Figure for Question 2.49 Test for water question 1 — Edexcel IGCSE Chemistry

This is the equation for the reaction.

2 \mathrm{H}_{2} \mathrm{O}_{2} \rightarrow 2 \mathrm{H}_{2} \mathrm{O}+\mathrm{O}_{2}

Give a chemical test for the presence of water.

- anhydrous / white copper(II) sulfate / copper sulfate / $\ce{CuSO4}$
- turns from white to blue

Allow:
- anhydrous / blue cobalt(II) chloride / cobalt chloride / cobalt(II) chloride paper
- turns from blue to pink

Ignore:
- water boils at 100 degrees C

Marking guidance:
- The colour-change mark depends on the reagent mark.

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2.49 Test for water question 1