What is pKb of the conjugate
base of X-281? (Assume 25 ∘C.) Express your answer numerically.
<Topic_8b_acidbase Relating pka and pKb 11 of 17 > Review Constants Periodic Table pk. = 4.96 Learning Goal: To understand the relation between the strength of an acid or a base and its pK, and pK, values. The degree to which a weak acid dissociates in solution is given by its acid-ionization constant K, . For the generic weak acid, HA, Submit Previous Answers ✓ Correct HA(aq) = A (aq) +H+(aq) and the acid-ionization constant is given by Conjugate pairs At 25 °C, for any conjugate acid-base pair KAH K = FA PK, +pKb = 14.00 Similarly, the degree to which a weak base reacts with H2O in solution is given by its base-ionization constant, Kb. For the generic weak base, B, Part B B(aq) + H2O(1) = BH(aq) + OH(aq) and the base-ionization constant is given by K= BH OH в) What is pKof the conjugate base of X-281? (Assume 25 °C) Express your answer numerically. View Available Hint(s) A R O m)? VO AED pK = 9.68 Submit Previous Answers X Incorrect; Try Again; 3 attempts remaining
From the given relationship, pKa + pKb = 14 at 25oC
i.e. pKb = 14 - pKa
here, pKa of X-281 is given as 4.96.
so, pKa = 4.96
If we assume the temperature to be 25oC,
Then, pKb = 14 - pKa
= (14 - 4.96)
so, pKb is 9.04
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