Chapter 18, Problem 18.53QP

Interpretation Introduction

Interpretation:

Need to calculate the coulombs of electricity required to produce 2.35 g of cobalt by the electrolysis of molten CoSO₄.

Concept introduction:

Electrolysis of molten CoSO₄ will produce cobalt at cathode by the following cell reaction.

${\text{Cathode (reduction) Co}}^{\text{2+}}{}_{\text{(aq)}}{\text{+2e}}^{\text{-}}\stackrel{}{\to }{\text{Co}}_{\text{(s)}}$

In the above reaction Co²⁺ ion accepts two electrons from cathode and get reduced into cobalt metals. Number of moles of cobalt produce can be calculated from mass of the cobalt produced.

$\text{Number}\text{of}\text{moles of cobalt (n)}\text{=}\frac{\text{Weight}}{\text{Atomic}\text{Mass}}$

From the half-cell reaction it was found that two moles of electrons will be needed to obtain one mole of cobalt.

So

$\begin{array}{l}\text{Number}\text{of}\text{moles of electrons = Number of moles of cobalt }\times \text{ 2}\\ \text{then}\\ \text{charges}\text{=}\text{Number}\text{of}\text{moles of electrons×Faraday}{\text{constant (96500C/mole e}}^{-}\text{)}\end{array}$

To find: Coulombs of electricity required to produce 2.35 g of cobalt by the electrolysis of molten CoSO₄.