The chemical reactions happening in this sequence are:

Nitrogen gas (N2) reacts with ammonia (NH3) to form ammonium sulfate ((NH4)2SO4):
N2 + 4NH3 --> (NH4)2SO4

Ammonium sulfate ((NH4)2SO4) dissociates into ammonia (NH3) and sulfuric acid (H2SO4):
(NH4)2SO4 --> 2NH3 + H2SO4

Ammonia (NH3) reacts with calcium nitride (Ca3N2) to form calcium hydroxide (Ca(OH)2) and ammonium ion (NH4+):
6NH3 + Ca3N2 --> 3Ca(OH)2 + 2NH4+

Overall, the chemical reactions involve the transformation of nitrogen gas, ammonia, ammonium sulfate, calcium nitride, and ammonium hydroxide.