Question:easy

Calculate the pOH of \(0.01\) M monobasic acid that is completely dissociated, at \(298\) K.

Show Hint

Complete dissociation gives [H+] = 0.01 M, so pH = 2 and pOH = 14 - pH.
Updated On: Oct 1, 2026
  • \(02\)
  • \(12\)
  • \(03\)
  • \(11\)
Show Solution

The Correct Option is B

Solution and Explanation

Step 1: Plan:
Find hydroxide ion concentration first, then take its negative logarithm.

Step 2: Hydroxide concentration:
Complete dissociation gives $[\text{H}^+] = 10^{-2}$ M. At 298 K, $K_w = [\text{H}^+][\text{OH}^-] = 10^{-14}$.
\[ [\text{OH}^-] = \frac{10^{-14}}{10^{-2}} = 10^{-12} \text{ M} \]

Step 3: Take the logarithm:
$\text{pOH} = -\log 10^{-12} = 12$.

Step 4: Check:
An acid solution has high pOH, so a value of 12 (not 2) makes sense.

Final Answer:
The pOH is 12, option (B). \[ \boxed{\text{pOH} = 12} \]
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