The conjugate base of the ammonium ion (NH4+) is ammonia (NH3). To understand this, let’s look at the definition of a conjugate base.
A conjugate base is what remains after an acid donates a proton (H+). When ammonium (NH4+) acts as an acid and donates a proton, it loses one hydrogen ion (H+), resulting in the formation of ammonia (NH3). This process can be represented by the following reaction:
NH4+ → NH3 + H+
In this reaction, NH4+ is the acid, while NH3 is the conjugate base formed. Thus, whenever you have an acid like NH4+, the conjugate base can be determined by identifying what remains after the acid has lost a proton.