A metal workshop stores copper sulfate solution in labelled containers. Fig. 1 shows particles in a sample of copper sulfate solution. The circles marked Cu...
Question 1 Report
A metal workshop stores copper sulfate solution in labelled containers. Fig. 1 shows particles in a sample of copper sulfate solution. The circles marked Cu are copper ions and the smaller circles are water molecules. The student heats the solution to obtain crystals.
(a) Name the type of particle labelled Cu. [1]
(b) What happens to water molecules when the solution is heated gently? [1]
(c) Give two differences between an ionic compound such as copper sulfate and a simple carbon compound such as methane. [3]
Answer Details
(a) The particle labelled Cu is a copper ion, \(\mathrm{Cu^{2+}}\). It is positively charged because copper atoms have lost electrons. [1 mark]
(b) On gentle heating, water molecules evaporate, changing into water vapour. Removing some water can make the solution concentrated enough for crystals to form on cooling. [1 mark]
(c) Ionic compounds and simple molecular substances differ in both their particles and structure.
- Copper sulfate contains ions, whereas methane consists of molecules.
- Copper sulfate has a giant ionic lattice, whereas methane has a simple molecular structure.
- Copper sulfate conducts electricity when molten or in solution because its ions can move; methane does not conduct.
Any two valid differences gain credit. [3 marks]
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