Question

100 mL of 0.2 N NaOH is mixed with 100 mL of 0.1 N HCl and the volume is made 1 L. The pH of the solution is:

Answer 1

Hi,

When 100 mL of 0.2 N NaOH is mixed with 100 mL of 0.1 N HCl and the volume is made 1 L. The pH of the solution is calculated as follows;

I would like to give you the shortest way to calculate the resultant concentration which you will finally use to calculate the pH;

So we can say that;

Resultant concentration = (M₁V₁) + (M₂V₂) /(V₁+ V₂)

This gives (0.2 x 100) + (0.1 x 100) / (100 + 100)

= 0.15 M

Then the pH= -log (0.15)

               pH= 0.8

I hope it helps and please note that this method you can use in many cases which may not be similar to this.