IGCSE Chem Electrochemistry

The diagram shows a failed attempt to copper-plate a pan.

Which action will plate the pan with copper?

• cooling the copper sulfate solution in an ice bath

• heating the copper sulfate solution to boiling point

• increasing the voltage from 3V to 6V

• making the pan the cathode and the copper the anode

The diagram shows the electroplating of a steel object.

A student made the following statements.

1. The object turns a reddish-brown colour.

2. The copper sulfate solution changes to a paler blue colour.

3. The copper electrode becomes smaller.

Which statements are correct?

• 1, 2 and 3

• 1 and 2 only

• 1 and 3 only

• 2 and 3 only

Which metal could not be used for electroplating by using an aqueous solution?

• chromium

• copper

• silver

• sodium

Which products are formed at the anode and cathode when electricity is passed through molten

lead(II) bromide?

• A

• B

• C

• D

The diagram shows an electrical cable.

Which statement about the substances used is correct?

• The coating is plastic because it conducts electricity well.

• The core is copper because it conducts electricity well.

• The core is copper because it is cheap and strong.

• The core is iron because it is cheap and strong.

The diagram shows an electrolysis circuit.

At which electrode is hydrogen formed?

• A

• B

• C

• D

The diagram shows apparatus used in an attempt to electroplate a metal ring with copper.

The experiment did not work.

What change is needed in the experiment to make it work?

• Add solid copper(II) sulfate to the electrolyte.

• Increase the temperature of the electrolyte.

• Replace the copper electrode by a carbon electrode.

• Reverse the connections to the battery.

Substance X was electrolysed in an electrolytic cell.

A coloured gas was formed at the anode and a metal was formed at the cathode.

What is substance X?

• aqueous sodium chloride

• molten lead bromide

• molten zinc oxide

• solid sodium chloride

The diagram shows apparatus for plating a spoon with silver.

Which statement is not correct?

• Silver would stick to the spoon because it is a very reactive metal.

• The metal electrode would be made from silver.

• The spoon would be connected to the negative of the power supply.

• The electrolyte would be a silver salt dissolved in water.

Three electrolysis cells are set up. Each cell has inert electrodes.

The electrolytes are listed below.

Cell 1 - aqueous sodium chloride

Cell 2 - concentrated hydrochloric acid

Cell 3 - molten lead(II) bromide

In which cells is a gas formed at both electrodes?

• 1 and 2

• 1 and 3

• 2 only

• 3 only