Question

87. In an experiment 0.04 F was passed through 400 ml
of a 1 M solution of NaCl. What would be the pH of
the solution after the electrolysis?
(1) 8 (2) 10 (3) 13 (4) 6​

Answer 1

Answer:

option 3 is correct

At electrolysis we get

Nacl+$H_{2} O---->NaOH(at anode)+1/2H_{2} +1/2Cl_{2}$(at cathode)

so for 1M solution of Nacl

The no of moles=molarity*volume in L

                           =1*0.4L

                           =0.4mole

since 1F produces=1 mole of NaOH

0.04F will produce=0.04 mole of NaOH

so 400ml of the solution contains=0.04 mol NaOH

Molar concentration of NaOH=0.04/0.4L=0.1M

$[OH^{-} ]=0.1M$

pOH=$-log[OH^{-} ]=1$

Hence pH=14-1=13