Final answer:
The reaction between ammonia (NH3) and sulphuric acid (H2SO4) to form ammonium sulfate ((NH4)2SO4) is an exothermic acid-base reaction.
Step-by-step explanation:
The reaction in question is:
NH₃ (g) + H₂SO₄ (aq) → (NH₄)₂SO₄ (aq)
This is an example of an acid-base reaction. When ammonia (NH₃), which acts as a base, reacts with sulphuric acid (H₂SO₄), which acts as an acid, they form ammonium sulfate ((NH₄)₂SO₄), a salt. This reaction can be thought of as NH₃ accepting protons from H₂SO₄, illustrating the concept of conjugate acid-base pairs. In this instance, (NH₄)^+ is the conjugate acid of NH₃, and SO₄^(2−) is the conjugate base of H₂SO₄. This reaction is also exothermic as it releases heat (standard enthalpy of formation).