Question

An aqueous solution has a pH of 7.25 .

(1) What is the pOH of this solution?

(2) What is the hydroxide ion concentration in this solution? M

(3) What is the hydrogen ion concentration in this solution? M

Answer 1

pH of a solution is the hydrogen ion concentration present in a solution.

It depends on the nature of the acid, whether it is a strong acid or weak acid.

Strong acid provides more H⁺ ions than a weak acid.

Suppose if we have a 0.1 M solution of HCl and another solution of 0.1 M acetic acid, then

The pH of HCl solution will be more because it provides more H⁺ ions , so it is a strong acid.

And acetic acid is called weak acid because it does not dissociate well and provide less H⁺ ions.

The formula for finding pH = - log[H⁺]

10^-7.25= [H⁺]

(3). [H⁺] = 5.624*10^-8M

Also,

[H⁺] [OH^-] =10^-14

[OH^-] = 10^-14 /5.624*10^-8

(2.) [OH^-] = 1.778 *10^-7M

pOH = -log[OH^-]

(1.) pOH = 6.75

We can also find pOH very easily by using the formula

14 = pH+pOH