Question

Question #df7ec

Answer 1

`"pH" = 1.60`

Explanation:

The pH of a solution is simply a measure of the concentration of hydrogen ions, `"H"^(+)`, which are sometimes called hydronium ions, `"H"_3"O"^(+)`.

More specifically, the pH of a solution is defined as

`color(blue)(bar(ul(|color(white)(a/a)"pH" = - log(["H"^(+)])color(white)(a/a)|)))`

Here `["H"^(+)]` represents the molarity, or molar concentration, of the hydrogen ions.

This means that all you have to do to find the solution's pH is take the negative log base `10` of the concentration of hydrogen ions.

In your case, this will get you

`"pH" = - log(2.5 * 10^(-2))`

Now, you can use the properties of the log function to say that

`"pH" = - [log(2.5) + log(10^(-2))]`

which gets you

`"pH" = - [log(2.5) + (-2) log10]`

`"pH" = - [log(2.5) - 2]`

`"pH" = 2 - log(2.5)`

You can say for sure that the pH of this solution is lower than `2`. You can play around with this even more to find

`"pH" = 2 - log(10/4)`

`"pH" = 2 - (log10 - log4)`

`"pH" = 2 - 1 + log4`

`"pH" = 1 + log4`

You can now say that the pH is higher than `1`. Finally, you can use a calculator to get the exact value

`color(green)(bar(ul(|color(white)(a/a)color(black)("pH" = 1 + log4 = 1.60)color(white)(a/a)|)))`