Calculate, please help me understand?

Question

Calculate the PH?
[H+] = 4.78 x 10^-2M
pOH = 4.56
[OH-] = 9.74 x 10^-3M
[H+] = 1.24 x 10^-8M

can you show me step by step for them be cause i do not understand correctly how to do it.

Answer 1

pH = -log [H+]

pH = 14 - pOH

pOH = -log [OH-]

those are the formulas you should need to use.

Answer 2

No problem.

Definition: pH = - log [H+]

You should get 1.32 for the first one. If not, you need help with using your calculator with exponents.

Also, for water at 25 C, [H+] x [OH-] = 10^-14

Take logs and change sign:

pH + pOH = 14