Question

The pH of an aqueous solution is 4.32. What is the [OH–]?

A.
6.4 x 10–1 M
B.
4.8 x 10–5M
C.
2.1 x 10–10 M
D.
1.6 x 10–14M

Answer 1

Answer: The concentration of hydroxide ion concentration is
`2.08* 10^(-10)`

Step-by-step explanation:

pH is defined as negative logarithm of hydrogen ion concentration. It is basically defined as the power of hydrogen ions in a solution.

To calculate the hydroxide ion concentration of the solution, we need to determine the pOH of the solution first and to do so, we calculate the pOH by the following equation:

`pH+pOH=14\\pOH=14-4.32=9.68`

pOH is defined as negative logarithm of hydroxide ion concentration. It is basically defined as the power of hydroxide ions in a solution.

The equation used to calculate pOH of the solution is given as:

`pOH=-\log[OH^-]`

pOH of the solution = 9.68

Putting values in above equation, we get:

`9.4=-\log[OH^-]`

`[OH^-]=antilog(-9.68)`

`[OH^-]=2.08* 10^(-10)`

Hence, the concentration of hydroxide ion concentration is
`2.08* 10^(-10)`

Answer 2

Answer;

C. 2.1 x 10–10 M

Explanation;

pKw=pH + pOH = 14

pOH = 14-4.32

=9.68

But; pOH = -log[OH]

[OH-]=10^(-9.68)

=2.089x10^-10M

≈ 2.1 x 10–10 M