Question

NaOH is added to the following reaction:

NH4+(aq) + H2O(l)-->H30+(aq)+NH3(aq)

Using Le Châtelier's Principle, state in which direction the equilibrium will shift in response to the change. Briefly defend your answer.

Answer 1

The reaction we are analysing:

NH4+(aq) + H2O(l)-->H30+(aq)+NH3(aq)

is mainly the equilibrium between NH3(aq) and acidic NH4+

note that

NH4+ is acidic since it can donate H+ ions as follow:

NH4+ <-> NH3 + H+

therefore

if we add NaOH, a strong base

expect:

NaOH(aq) --> Na+ + OH-

OH- will react wit NH4+ as follows:

NH4+ + OH -- NH3 + OH

therefore, we have 2 important things to consider:

NH4+ is decreasing in concentration

NH3(aq) is increasing in concentration

these two actions will shift strongly toward MORE NH4+ and H2O production, i.e. the left side

since we must counter balance the loss in NH4+ and gain in NH3