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

Question

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

anonymous · Answer

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.

onepieceftw · Answer

Like this?

$$[1.0\times10^{-14}][4.2\times10^{-5}]$$

onepieceftw · Answer

@ghuczek

anonymous · Answer

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

onepieceftw · Answer

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

onepieceftw · Answer

Pardon me, 2.38 * 10^-10

onepieceftw · Answer

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