To find the concentration of hydroxide ions [tex]\([OH^-]\)[/tex] in an aqueous solution when the [tex]\(pH\)[/tex] is given, you can follow these steps:
1. Calculate the [tex]\(pOH\)[/tex]:
The relationship between [tex]\(pH\)[/tex] and [tex]\(pOH\)[/tex] in water at 25°C (298 K) is given by:
[tex]\[
pH + pOH = 14
\][/tex]
Given [tex]\(pH = 4.32\)[/tex], we can find [tex]\(pOH\)[/tex] as follows:
[tex]\[
pOH = 14 - pH = 14 - 4.32 = 9.68
\][/tex]
2. Calculate the [tex]\([OH^-]\)[/tex]:
The concentration of hydroxide ions in the solution can be calculated using the formula:
[tex]\[
[OH^-] = 10^{-pOH}
\][/tex]
Substituting the value of [tex]\(pOH\)[/tex]:
[tex]\[
[OH^-] = 10^{-9.68}
\][/tex]
3. Result:
The numerical value of [tex]\(10^{-9.68}\)[/tex] is:
[tex]\[
[OH^-] = 2.1 \times 10^{-10} M
\][/tex]
Therefore, the correct answer is:
[tex]\[
\text{C. } 2.1 \times 10^{-10} M
\][/tex]
