Chapter 6.4 Electrolysis of aqueous solutions

Question 1

What three products do you get when brine (concentrated sodium chloride solution) is electrolysed?

Answer 1

• Chlorine gas is produced at the anode (positive electrode).
• Hydrogen gas is produced at the cathode (negative electrode).
• Sodium hydroxide solution is also formed.

Question 2

Why is hydrogen produced at the cathode?

Answer 2

This is because as H+ (aq) ions are discharged from solution in preference to Na+ (aq) ions.

Question 3

Why is chlorine produced at the anode?

Answer 3

This is because Cl- (aq) ions are discharged from solution in preference to OH- (aq) ions.

Question 4

What is the summary of the electrolysis of brine?

Answer 4

Sodium chloride solution ===> hydrogen gas + chlorine gas + sodium hydroxide solution