JEE MAIN - Chemistry (2017 (Offline) - No. 19)
pKa of a weak acid (HA) and pKb of a weak base (BOH) are 3.2 and 3.4, respectively. The pH of their salt (AB) solution is :
6.9
7.0
1.0
7.2
Penjelasan
The salt (AB) given is a salt is of weak acid and weak base. Hence its pH can be calculated by
the formula
$$ \therefore $$ pH = 7 + $${1 \over 2}p{K_a} - {1 \over 2}p{K_b}$$
= 7 + $${1 \over 2}\left( {3.2} \right) - {1 \over 2}\left( {3.4} \right)$$
= 6.9
$$ \therefore $$ pH = 7 + $${1 \over 2}p{K_a} - {1 \over 2}p{K_b}$$
= 7 + $${1 \over 2}\left( {3.2} \right) - {1 \over 2}\left( {3.4} \right)$$
= 6.9