Ions & Ionic Bonds (Cambridge (CIE) IGCSE Chemistry): Exam Questions

A student is given a white solid.

The solid is either an ionic compound or a simple molecular compound.

Plan an experiment to find out which of these the solid is.

Your plan must use common laboratory apparatus and the solid provided. No other chemicals should be used, apart from distilled water.

Your plan must include:

• the apparatus needed

• the method to use and the observations to make

• the variables to control

• how the observations are used to decide whether the solid is ionic

You may draw a diagram to help answer the question.

A student investigates four solids, A, B, C and D.

For each solid the student finds out whether it melts when heated in a Bunsen flame, whether the solid conducts electricity, whether it dissolves in water, and whether the solution formed conducts electricity.

The results are shown in Table 1.1.

Table 1.1

Identify which solid is an ionic compound.

Give two results from Table 1.1 that support your answer.

The student concludes that solid C is a metal.

State the result in Table 1.1 that supports this conclusion.

The student tests the solutions using the same pair of electrodes each time, without washing them between tests.

Explain why this could affect the results.

A student tests whether different substances conduct electricity.

The apparatus used is shown in Fig. 1.1. The substance being tested is placed in the dish.

Fig. 1.1

Name apparatus X.

Extended Tier Only

The student places solid sodium chloride in the dish and switches on the power supply.

Describe and explain what is seen.

The student dissolves the sodium chloride in distilled water, pours the solution into a clean dish and repeats the test.

Describe what is seen.

The student uses distilled water to make the solution, rather than tap water.

Suggest why.