chemical reactions - electrolysis of an aqueous solution

Question 1

what do water molecules form?

Answer 1

hydroxide and hydrogen ions

Question 2

when is hydrogen produced at the cathode during electrolysis of an aqueous solution?

Answer 2

if the metal is more reactive than hydrogen

Question 3

what will form at the anode in an aqueous solution?

Answer 3

oxygen gas unless the aqueous solution contains halide ions, then a halogen will be produced at the anode

Question 4

what electrodes are used during electrolysis of an aqueous solution?

Answer 4

platinum inerts (unreactive)

Question 5

what would happen during the electrolysis of a copper sulfate solution?

Answer 5

1. copper is less reactive than hydrogen so copper will be produced at the cathode
   Cu2+ +2e- -> Cu
2. oxygen gas is produced at anode as no halide is present.

4OH- -> O2 + 2H2O + 4e-
4OH- - 4e- -> O2 + 2H2O

Question 6

what happens during the electrolysis of sodium chloride?

Answer 6

1. at the cathode, hydrogen will be produced as sodium is more reactive than hydrogen
   2H+ + 2e- -> H2
2. at the anode, chlorine gas is formed as chloride is a halide.
   2Cl- -> Cl2 + 2e-
   2Cl- - 2e- -> Cl2