A student investigates whether potassium chloride conducts electricity.
The student sets up a circuit containing a power supply, a bulb and two carbon electrodes. The student places the electrodes in each sample in turn and records whether the bulb lights.
The table shows the results.
| Sample | Does the bulb light? |
|---|---|
| solid potassium chloride | no |
| potassium chloride dissolved in water | yes |
| pure water | no |
Potassium chloride contains potassium ions, K+\mathrm{K^{+}}K+, and chloride ions, Cl−\mathrm{Cl^{-}}Cl−. Give the formula of potassium chloride.
Give a reason why the student also tested pure water.
The student repeats the test with sugar dissolved in water. The bulb does not light. Sugar is a covalent compound. Suggest why the sugar solution does not conduct electricity.
Explain the results shown in the table. Your answer should refer to the structure and bonding in potassium chloride. You should also predict and explain whether molten potassium chloride would conduct electricity.
56 exam-style questions on Edexcel GCSE Chemistry 2.3 Ionic bonding, covering 2.3.1 Ions and the formation of ionic bonds, 2.3.2 Naming and deducing formulae of ionic compounds, and 2.3.3 Giant ionic lattices. Each one has a worked solution and a mark scheme showing where the marks go.