Chemistry PKb of weak base titrated with strong acid

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The discussion centers on the pK values of a weak base being titrated with a strong acid. The key point is that the halfway point occurs at pH 9.2, indicating that pOH equals pKb, which is calculated to be 4.8. However, there is confusion regarding the correct pKb value, with some participants asserting that the solution indicating pKb = 9.2 is incorrect. The conversation highlights the need for clarity on the relationship between pKa and pKb in this context. Ultimately, the accuracy of the provided solutions is questioned, emphasizing the importance of understanding these concepts in titration scenarios.
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Homework Statement
(see below)
Relevant Equations
titration curve
pH + pOH = 14

at halfway point:
pH=pKa
pOH=pKb
titration curve.png


What is true about the pK of the analyte?
a) pKa = 9.2
b) pKb = 9.2
c) pKb = 4.8
d) pKa = 11.7

The halfway point is at point 4, at approximately pH=9.2. Therefore, the pOH = pKb = 4.8, and I think the answer is c).
The solution says b) is the correct answer. Could anyone explain why, or whether or not my answer is correct? Thanks.
 
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Solution is wrong.

Not that you are entirely right, c is not the only correct answer.
 
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