C6.4 - Electrolysis Of Aqueous Solutions (Kind of confused is water produced at eh)

Question 1

What do you get when electrolysing Brine?

Answer 1

Chlorine gas, hydrogen gas, sodium hydroxide

Question 2

What happens at the anode in the electrolysis of brine (sodium chloride solution)?

Answer 2

The Cl- ions are attracted, loose an electron being oxidised and then bond to form Cl2

Question 3

Why is sodium hydroxide produced in the electrolysis of sodium chloride solution (brine)?

Answer 3

The Cl- and H+ ions are removed to leave Na+ and OH- ions, which are a solution of sodium hydroxide, NaOH

Question 4

You need to practice half equations

Answer 4

Ok

Question 5

In the electrolysis of brine which Ions are attracted to the cathode?

Answer 5

H+ and Na+

Question 6

If two ions are attracted to the electrode which one will be discharged?

Answer 6

The less reactive one

Question 7

In the electrolysis of brine which ions are discharged at the cathode?

Answer 7

H+

Question 8

Why are H+ ions discharged at the cathode not Na+?

Answer 8

They are the least reactive

Question 9

Which extra ions will be present when electrolysing an aqueous solution?

Answer 9

In aqueous solutions, there will be H+ ions and hydroxide (OH-) ions from the water

Question 10

At the cathode when electrolysing aqueous solutions, which ions are present and which one will be produced?

Answer 10

When electrolysing aqueous solutions, at the cathode there will be H+ ions and metal ions present. Hydrogen will be produced if the metal ions form a metal more reactive than hydrogen, and metal if the metal ions form a metal less reactive than hydrogen.

Question 11

At the cathode the ___ reactive element is discharged

Answer 11

Less

Question 12

In the electrolysis of aqueous solutions what is formed at the anode when:

• halide ions are present
• halide ions are not present

Answer 12

If OH- ions and halide ions are present, molecules of chlorine, bromine or iodine will be formed

If OH- ions and no halide ions are present, then the OH- ions are discharged and oxygen is formed
(And water)

Question 13

When and aqueous solution of CuSO4 is electrolysed what is produced and why?

Answer 13

Copper is less reactive than hydrogen so is produced at the cathode. And there are no halide ions present so oxygen (and water?) is produced at the anode