AP Chemistryeasymcq1 pt
A weak acid has pKa = 4.75. What is the pKb of its conjugate base at 25 °C?
A.4.75
B.9.25
C.14.00
D.2.38
Explanation
Core Concept
Conjugate constants multiply to Kw, so pKa + pKb = pKw = 14.00 at 25 °C. Subtracting gives pKb = 14.00 - 4.75 = 9.25. A weak base has a large pKb precisely because its conjugate acid is comparatively strong.
Correct Answer
B9.25
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