A shampoo has a pH of 8.67. What is the [H3O+] in the shampoo?

Answer 1

If the pH is 8.67, you can calculate the concentration of the H3O+ ion by getting the inverse log of 8.67.

Using today's typical calculator, enter 2nd log, enter 8.67 and then get the result.

We old fashioned folks used to use a slide rule for this stuff.