Question

The pKa of HF is 3.2. Determine the pKb of its conjugate base?

a) 10.8
b) 3.2
c) 6.8
d) 13.2

Answer 1

The pKb of the conjugate base of HF is found by subtracting the pKa of HF from 14. Given that the pKa of HF is 3.2, the pKb would be 10.8.

Step-by-step explanation:

The question is asking to determine the pKb for the conjugate base of hydrofluoric acid (HF), given the pKa of HF is 3.2. The relationship between pKa and pKb for a conjugate acid-base pair is given by the equation pKa + pKb = 14.00. This is based on the fact that the ionization constants for an acid (Ka) and its conjugate base (Kb) are related through the autoionization constant of water (Kw), where Kw = Ka * Kb and pKw = pKa + pKb. Since pKw is 14 at 25°C, we can calculate the pKb for the conjugate base of HF as follows:

pKa + pKb = 14.00
pKb = 14.00 - pKa
pKb = 14.00 - 3.2
pKb = 10.8

Therefore, the correct answer is a) 10.8.