Chapter 21, Problem 21.140P

Interpretation Introduction

Interpretation:

The liters of $H_2$ formed from per $kg$ of $Zn$ has to be calculated under given conditions.

Concept Introduction:

An electrochemical cell is a device in which a redox reaction is used to convert chemical energy into electrical energy. Such device is also known as the galvanic or voltaic cell.

Galvanic cell consists of two half-cells. The redox reaction occurs in these half-cells. The half-cell in which the reduction reaction occurs is known as the reduction half-cell, whereas the half-cell in which the oxidation reaction occurs is known as the oxidation half-cell.

Oxidation: It is the loss of electrons by a species and thus oxidation number is increased.

Reduction: It is the gain of electrons by a species and thus oxidation number is decreased

According to Faraday’s Law the substance formed at electrode will directly depends on the charge flowing in a cell.

The Standard Gibb’s free energy change and the standard cell potential are related as followed:

$\begin{array}{l}\text{Δ}°\text{G}\text{=}\text{-nFE}{°}_{\text{cell}}\\ where,\\ \boxed{\begin{array}{l}\text{n - Number of electrons involved per equivalent of the net redox reaction in the cell}\\ \text{F - Faraday’s Constant }\left(\text{96500 C}\right)\\ {\text{E°}}_{\text{cell}}\text{- Standard cell potential}\text{.}\end{array}}\end{array}$

The Nernst equation depicts the relationship between $E_{cell}$ and ${\text{E}}^{\text{o}}{}_{\text{cell}}$ as follows,

$\begin{array}{l}{\text{E}}_{\text{cell}}{\text{=E}}^{\text{o}}{}_{\text{cell}}-\frac{0.0592V}{n}\log Q\\ \\ \boxed{\begin{array}{c}where,{\text{E}}_{\text{cell}}=cellpotential\\ {\text{E}}^{\text{o}}{}_{\text{cell}}=\text{Standard}cellpotential\\ n=No.ofelectrons\\ Q=\text{Reaction}Quotient\end{array}}\end{array}$