Question

How long does it take, in seconds, to electrolyze 1 mole of water in acidic solution at a current of 10 amperes? Given: O2 (g) + 4 H+ + 4 e- → 2 H2O 2 H+ + 2 e- → H2 (g)

• A.

  3.9 x 10⁴

• B.

  1.9 x 10⁴

• C.

  7.7 x 10⁴

• D.

  4.8 x 10³

• E.

  9.7 x 10³

Answer 1

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

For one mole of water above reaction is wriiten as

(1/2)O2 + 2H+ + 2e-----> H2O

H2 + 2e- -----> 2H+

Electrolysis of water is

H2O ------> H2 + (1/2)O2

For 1 mole of water to be electrolysed ,moles of electron involved = 2 mol

Charge on 2 mol of electrons = 2F = 2 x 96500 = 193000C

Current passed = 10 A

Charge required = 193000C

Time for electrolysis to take place = 193000/10

= 19300 sec

= 1.9 x 104 sec

Option B is correct