# PH question, I really don't get this!

## Homework Statement

What is the [H3O+] of acid rain with a pH of 4.23?

pH = -log[H30+]
pOH = -log[OH-]
pH + pOH = 14

## The Attempt at a Solution

the four possible choices are
a. 1.7 x 10^-10
b. 5.8 x 10^-5
c. 2.3 x 10^-4
d. 1.7 x 10^5

You are given the pH and need to calculate the concentration of the $$H_{3}O^+$$ ions. Which equation should you use?

I know I have to use the first one but I don't know how to do the reverse of it

Since pH = -log[H30+] or pH = -log[H+]
H3O+/H+ = 10^(-pH)

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But I dont get how to plug it in on my calculator

But I dont get how to plug it in on my calculator

10^(-pH)
10 to the -pH power.

Oh okay I got the answer thank you so much!