(a) What is the change in pH when [OH-] increases by a

Solution 14P

Step 1

(a) Here we have to find out what is the change in pH when [OH-] increases by a factor of 10.

It is known that, [H3O+] = -------(1)

And  pH = -log [H3O+] ------------------(2)

From the above equation, it has been seen that the concentration of [H3O+] is inversely proportional to the [OH-] ion. Hence if [OH-] increases by a factor of 10, then [H3O+] will decrease by factor 10.

Then, pH = -log [H3O+]

                = -log [1/10]

   = -log [10-1]

   = 1 log 10

   = 1

Thus when [OH-] increases by a factor of 10 then pH also increases by a value of 1.