Question

How does pH affect the nernst equation?

Answer 1

Hint: pH is the potential of hydrogen or the power of hydrogen. It is defined as the negative logarithm of the hydrogen ion concentration. It helps in determining the strength of the acid and the base. The pH of acid is generally less than 7. The pH of base is more than 7 and for neutral solution is pH is equal to seven.

Complete step by step answer:
$${E_{cell}} = {E^o}_{cell} - \dfrac{{0.059}}{n}\log \dfrac{{[product]}}{{[reac\tan t]}}$$
Let us take the example of hydrogen here for understanding. So the reaction of hydrogen is:
$$\dfrac{1}{2}{H_2} \to {H^ + } + 1{e^ - }$$
So now for substituting the values in nernst equation
The n will be equal to 1 as 1 mole of the electron has been used.
The product is hydrogen ion and the reactant is $${[{H_2}]^{\dfrac{1}{2}}} = 1$$as only hydrogen is present.
The value of $${E^o}_{cell}$$for hydrogen is 0.
So now putting all these value in nernst equation we get:
$${E^o}_{cell} = 0 - \dfrac{{0.059}}{1}\log \dfrac{{[{H^ + }]}}{1}$$
On simplifying we get:
$${E^o}_{cell} = 0.059[ - \log [{H^ + }]]$$
We know that
$$pH = - \log [{H^ + }]$$
So on substituting the formula of pH in the nernst equation we get:
$${E^o}_{cell} = 0.059 \times pH$$
So from the above relation or equation we get to know that pH is directly proportional to nernst equation. So on increasing the pH the increase in value of $${E^o}_{cell}$$ or nernst equation increases.

Note: pH scale helps in determining the nature of the substance. The value of pH scale ranges from 0 to 14. This scale is logarithm. The formula of pH is $$pH = - \log [{H^ + }]$$. To calculate the pH we should know the hydrogen ion concentration in the substance.