Question

An aqueous solution has a hydronium ion concentration of `6 * 10^-9` mole per liter at 25°C. What is its pH?

Answer 1

`pH=8`

Explanation:

The pH of a solution could be calculated using the concentration of hydronium `H_3O^+` by: `pH=-log[H_3O^+]`

Therefore, `pH=-log(6xx10^(-9))=8.22 =8 ("1 significant figures")`

Acids & Bases | Nature, Strength & pH Scale.

Answer 2

`pH =8.22`

Explanation:

So what is `pH`?

Here it is simply the function `pH=-log_10[H_3O^+]`, `pH` derives from the French `"pouvoir hydrogene"`, `"the power of hydrogen"`.

We have `[H_3O^+]` and we have a calculator, so we press the buttons.

It is worthwhile to review the logarithmic function, and see why the use of logarithms (and slide rules) was absolutely widespread among scientists and engineers in a pre-calculator world.