Question

Can someone help me understand this?
Calculate the pH of a solution with a concentration 4.2 * 10^-5 molar OH-

Answer 1

There are different ways of doing this. You can find the concentration of the hydronium ion. \[\color{green}{K_w = [H^{+}][OH^{-}]}\]
Then,\[\color{green}{pH = - \log [H^+]}\] Another approach would be to find pOH first.

Answer 2

Like this?

\[[1.0\times10^{-14}][4.2\times10^{-5}]\]

Answer 3

@ghuczek

Answer 4

Divide Kw by the concentration of the hydroxide ion to find the concentration of the hydronium ion.

Answer 5

What should the answer look like? I'm getting 2.38

Answer 6

Pardon me, 2.38 * 10^-10

Answer 7

Alright man, I got it! Thanks! answer is 9.62