Question

What is the pH of a solution whose `H_3O^+` concentration is `1*10^-9`?

Answer 1

9

Explanation:

pH of an acid is given by `-log[H_3O]`

Where `[H_3O]` is concentration of `[H_3O]` ions

So, pH is `-log(10^-9)`

`=-(-9)`

`=9`

Note: The logarithm is to the base 10.