Important

Question 1

What is brine solution

Answer 1

conc. NaCl(aq)

Question 2

What is the observation of anode when chlorine gas formed in electrolytic cell (with universal indicator)

Answer 2

Solution around anode becomes red and then colourless
red: some chlorine gas formed dissolves in water to give chlorine water which is acidic and
colourless: HOCl has bleaching power

Question 3

why will the actual volume of chlorine collected in the electrolytic cell may be smaller than that of hydrogen gas

Answer 3

some chlorine gas dissolves in water

Question 4

What is Na/Hg(l) ? a mixture /compound

Answer 4

a mixture, alloy

Question 5

Describe the set up of anodization of aluminium (electrodes, electrolyte)

Answer 5

Electrolysis
anode: Al object to be plated
cathode: Pt/ C(s)
electrolyte: dilute sulphuric acid

Question 6

Describe the set up of electroplating

Answer 6

Electrolysis
anode: metal used for electroplating
cathode: object to be plated
electrolyte: better to use electrolyte that contain the metal ions of the metal used for electroplating

Question 7

Can the object to be electorplated be a plastic? What treatment yuou need to do?

Answer 7

If it is made of plastic, electrical conducting graphite should be added to the plastic surface before electroplating.

Question 8

When do we need to do purification of metals

Answer 8

The metals extracted by carbon reduction may contain impurities. The metals extracted can be purified by electorlysis.