Question

The $pH$ of aqueous solution of ammonium formate is $\left( p K_{a}\right.$ of $HCOOH =3.8$ and $pK _{b}$ of $\left.NH _{3}=4.8\right)$

• A. 7
• B. 6
• C. 6.5
• D. 8.9

Answer 1

Answer: (C)

6.5

Answer 2

For a salt of weak acid and weak base, its $pH = 7+\frac{1}{2}pK_{a^{-}} \frac{1}{2}pK_{b}$ $= 7+\frac{1}{2}\times3.8-\frac{1}{2}\times4.8 = 6.5$