Question

The pK a of a weak acid, HA, is 4.80. The pK_b of a weak base, BOH is 4.78. The pH of an aqueous solution of the corresponding salt, BA, will be

(a) 9.22 

(b) 9.58

(c) 4.79 

(d) 7.01

Answer 1

(d) : Given that pK_a = 4.8 and pK_b = 4.78
Therefore,  pH = 7 + 1/2 (pK a – pK_b )
= 7 + 1/2 (4.80 – 4.78) = 7.01