Electrolysis of aqueous solutions

Question 1

What do the ions that are discharged at electrodes when the solution is electrolysed depend on?

Answer 1

• Relative reactivity of all the ions in the solution

Question 2

What is produced at the cathode?

Answer 2

• Hydrogen

- If metal is more reactive than hydrogen

Question 3

What is produced at the anode?

Answer 3

• Oxygen

- If OH- + halide ions are present, halogens are produce

Question 4

Describe the electrolysis of copper sulfate solution?

Answer 4

• Copper is less reactive than hydrogen, coats cathode

- No OH-/halides so oxygen + water is produced at anode

Question 5

Describe the electrolysis of sodium chloride solution.

Answer 5

• Sodium is more reactive than hydrogen, hydrogen is produced
• Chloride ions are present, chlorine gas at anode

Question 6

What are the tests for Chlorine, Oxygen, Carbon dioxide, hydrogen?

Answer 6

• Chlorine: turns litmus paper white
• Oxygen: splint relights
• CO2: limewater turns cloudy
• Hydrogen: pop sound with lighted splint