# What is the pH of a .20 M NH_4NO_3 solution?

Aug 11, 2017

pH = 4.97

#### Explanation:

Ammonium nitrate is the salt of a weak base and a strong acid so we would expect it to be slightly acidic due to salt hydrolysis:

$\textsf{N {H}_{4}^{+} r i g h t \le f t h a r p \infty n s N {H}_{3} + {H}^{+}}$

The position of equilibrium lies well to the left such that $\textsf{p {K}_{a} = 9.24}$.

From an ICE table we get this expression which can be used to find the pH of a weak acid:

sf(pH=1/2(pK_a-log[acid])

$\therefore$sf(pH=1/2(9.24-log(0.2))

sf(pH=1/2(9.24-(-0.699))

$\textsf{p H = 4.97}$