Question

1. Liquid (anhydrous) ammonia, NH3(l), with a boiling point of –33 °C, is often used as an alternate solvent to water. It forms strong hydrogen bonds and the polar molecules can solvate ionic compounds. Anhydrous ammonia also undergoes autoionization. Therefore, there can be acidic, neutral, or basic species in solutions of liquid ammonia.

a) Write the chemical equation, using the Brønsted‐Lowry perspective, that describes the autoionization of NH3(l). (Hints: for water this equation is 2H2O(l) ⇌ H3O+(aq) + OH–(aq); X(am) denotes a solute solvated by ammonia) ?

Answer 1

a) 2NH3 (l) <--------------------> NH4+ (aq) + NH2- (aq)

or

NH3 (l) + NH3(l) ------------------> NH4+(aq)          +    NH2- (aq)

acid           base                          conjugate acid    conjugate base

NH3 can act as acid and base in autoionisation