Question

Select the correct answer.

What is the [OH-] of a solution with pH 5.75?
OA. 5.6 10-'M
OB. 1.3 x 10-6 M
OC. 7.6 x 10-1M
OD. 9.2 x 10-1M​

Answer 1

A. 5.6 10⁻⁹M

Step-by-step explanation:

Hello,

In this case, we should know that the pH it related with the pOH by:

`pH+pOH=14`

This allows us to compute the pOH and subsequently the concentration of hydroxyl ions, [OH-], as shown below:

`pOH=14-pH=14-5.75=8.25`

Thus, since pOH is mathematically defined as:

`pOH=-log([OH^-])`

We finally compute [OH-] as follows:

`[OH^-]=10^(-pOH)=10^(-8.25)\\\\`

`[OH^-]=5.6x10^(-9)M`

Hence, for sure the answer is A. 5.6 10⁻⁹M

Best regards.