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

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Answer 1 · 2017-08-11T18:13:33

pH = 4.97

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:

#sf(NH_4^+rightleftharpoonsNH_3+H^+)#

The position of equilibrium lies well to the left such that #sf(pK_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])#

#:.##sf(pH=1/2(9.24-log(0.2))#

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

#sf(pH=4.97)#