Core practical - electrolysis of copper sulfate solution. p1

Question 1

aim:

Answer 1

To investigate the electrolysis of copper sulfate solution using inert (unreactive) electrodes.

Question 2

method: (6)

Answer 2

1- Pour some copper sulfate solution into a beaker.
2- Place two graphite rods into the copper sulfate solution. Attach one electrode to the negative terminal of a dc supply, and the other electrode to the positive terminal.
3- Completely fill two small test tubes with copper sulfate solution and position a test tube over each electrode as shown in the diagram.
4- Turn on the power supply and observe what happens at each electrode.
5- Test any gas produced with a glowing splint and a burning splint.
6- Record your observations and the results of your tests.

Question 3

observations and gas tests at positive and negative electrodes: (3)

Answer 3

positive electrode negative electrode

observations brown/pink solid forms bubbles of a colourless gas form

gas test gas relights a glowing splint

Question 4

Suggest an explanation for why it may be difficult to obtain positive results for the tests on gases.

Answer 4

The volumes of gas collected are very small, making it difficult to carry out the tests.