Electrolysis

What is observed during the electrolysis of aqueous copper(II) sulfate using carbon electrodes?

• A pink solid is deposited on the anode

• Bubbles form on the negative electrode

• The colour of the solution fades.

• The negative electrode becomes smaller.

Four processes using electrolysis are listed.

1 the electrolysis of concentrated aqueous sodium chloride 2 the electrolysis of dilute sulfuric acid

3 the extraction of aluminium from pure aluminium oxide

4 the purification of copper using aqueous copper(II) sulfate

Which processes produce oxygen at one of the electrodes?

• 1 and 2

• 2 and 3

• 2 and 4

• 3 and 4

A simple cell can be made using two different metals as the electrodes and an aqueous solution as the electrolyte.

Which statements about simple cells are correct?

1 A greater voltage is produced using magnesium and silver than using magnesium and copper.

2 The electrolyte is an aqueous solution containing both positive and negative ions.

3 The more reactive metal will release electrons

• 1, 2 and 3

• 1 and 3 only

• 1 only

• 2 and 3 only

Three different solutions were electrolysed using inert electrodes.

solution 1 aqueous sodium chloride

solution 2 concentrated hydrochloric acid

solution 3 dilute sulfuric acid

Which solutions produce hydrogen at the negative electrode?

• 1, 2 and 3

• 1 and 2 only

• 1 only

• 2 and 3 only

Molten salts of four metals are electrolysed.

The ions of which metal require the smallest number of electrons for one mole of atoms to be liberated during electrolysis?

• aluminium

• calcium

• iron

• sodium

Aluminium is manufactured from aluminium oxide by electrolysis. The compound cryolite is used in this process. Which statement about cryolite is correct?

• It is the common name for aluminium oxide.

• It is used to dissolve the aluminium oxide.

• It is used to make the positive electrode.

• It is used to make the negative electrode.

What is the correct equation for the reaction taking place at the negative electrode when molten magnesium chloride is electrolysed using inert electrodes?

• Cl ^– → Cl + e^–

• 2Cl^– → Cl₂ + 2e^–

• Mg⁺ + e^– → Mg

• Mg²⁺ + 2e^– → Mg

Which method is used to obtain chlorine from aqueous sodium chloride?

• crystallisation

• distillation

• electrolysis

• filtration