Question

Answer the following questions:

a) Calculate the EMF of the cell for the reaction
$M{g}_{\left(s\right)}+2A{g}_{\left(aq\right)}^{+}\to M{g}_{\left(aq\right)}^{2+}+2A{g}_{\left(s\right)}$.
Given :

$E_{M{g}^{2+}/Mg}^0=-2.37V$
$E_{A{g}^{+}/Ag}^0=0.80V$
$\left[M{g}^{2+}\right]=0.001M;\left[A{g}^{+}\right]=0.0001M$

b) What are fuel cells?

Answer 1

a)
$E_{cell}^0=E_{Ag}^0-E_{Mg}^0$

$E_{cell}^0=0.80-(-2.37)=3.17$ V
$E_{cell}=E_{cell}^0=-\frac{0.0592}{n}log\frac{\left[M{g}^{2+}\right]}{[A{g}^{+}{]}^2}$

$E_{cell}=3.17-\frac{0.0592}{2}log\frac{0.001}{(0.0001{)}^2}$

$E_{cell}=3.022$ V
b)
Fuel cells: The galvanic cells in which the energy of the combustion of fuels is directly converted into electrical energy are called fuel cells. Usually, hydrogen gas or methanol is used as a fuel. An example of fuel cell is $H_2-O_2$ fuel cell.