Electrolysis (Level 2)

A few drops of litmus solution were added to concentrated rubidium chloride solution and the resultant solution was electrolysed using platinum electrodes.

Which statement is true?

• A greenish-yellow gas is formed at the cathode.

• The anode decreases in mass.

• The pH of the electrolyte decreases.

• The solution turns purple around the cathode.

Which element requires the smallest number of electrons for one mole of atoms to be liberated during electrolysis?

• alumnium

• calcium

• copper

• sodium

The diagrams show an electrolysis experiment using inert electrodes. Which could be liquid Y?

1 - aqueous copper (II) sulfate; 2 - aqueous sodium nitrate;

3 - concentrated aqueous sodium chloride;

4 - dilute sulfuric acid

• 4 only

• 1 and 4 only

• 2 and 4 only

• 2, 3 and 4 only

A coil of clean copper wire is suspended in aqueous silver nitrate. Crystals of silver are deposited on the copper wire.

Which statement is not correct?

• The copper is oxidised.

• The total mass of silver crystals increases gradually.

• The total number of positive ions in the solution is unchanged.

• The solution turns blue.

In an electrolysis experiment, the same amount of charge deposited 54.0 g of silver and 8.5 g of vanadium.

What is the charge on the vanadium ion?

• 1+

• 2+

• 3+

• 4+

With reference to the diagram below, which of the following statements is correct?

• Copper electrode is the negative electrode.

• Metal X is below copper in the reactivity series.

• The mass of the copper electrode decreases.

• The mass of the metal X electrode decreases.

When electrolysed using inert electrodes, which dilute solution would produce the greatest increase in mass of the cathode?

• aluminum sulfate

• copper (II) sulfate

• lead nitrate

• silver nitrate

A sample of copper contains a metal impurity which is below copper in the reactivity series. The diagram shows the apparatus used for refining the sample.

The loss in mass of the anode is 50 g and the gain in mass of the cathode is 45 g.

What is the percentage purity of this sample of copper?

• 10.0%

• 11.1%

• 90.0%

• 95.0%

What products are formed when concentrated aqueous potassium chloride is electrolysed?

• anode - chlorine gas ; cathode - hydrogen gas

• anode - chlorine gas; cathode - potassium

• anode - oxygen gas; cathode - hydrogen gas

• anode - oxygen gas; cathode - potassium

A simple cell is set up. Which pair of electrodes would give the largest magnitude on the voltmeter reading?

• copper and zinc

• magnesium and copper

• silver and magnesium

• zinc and iron