Question

In an experiment 0.04 Faraday of electricity passed through a solution of 400 ml of 1 molarity NaCl what would be the pH of solution after electrolysis ? please explain

Answer 1

At electrolysis we get: NaCl + H2O --> NaOH (at anode) + 1/2H​​2 + 1/2Cl​​2 (at cathode)

Now, for 1M solution of NaCl, the no. of moles = molarity x volume in L = 1 x 0.4L = 0.4 mole

Since, 1F produces = 1 mole of NaOH

So, 0.04F will produce = 0.04 mole of NaOH

So, 400 ml of the solution contains = 0.04 mol NaOH

Hence, molar concentration of NaOH = 0.04/0.4L = 0.1 M

Hence. [OH-]=0.1M
pOH = -log​[OH-] = 1
Hence., pH = 14-1 = 13