Q.Give two equations to illustrate the chemical behaviour of phosphine.

Step 1. Illustrate phosphine's (weak) basic character.

Unlike ammonia, phosphine is only very weakly basic, but it can still react with the strong hydrohalic acids to form phosphonium salts, in which the lone pair on phosphorus is donated to a proton: PH3 + HI -> PH4I (phosphonium iodide). This salt is, however, easily hydrolysed straight back to phosphine by water (PH4I + H2O -> PH3 + H3O+ + I-), underlining just how weak this basicity really is compared with ammonia's much more robust NH4+ salts.

Step 2. Illustrate phosphine's reducing character. …

Select one reaction demonstrating phosphine's (weak) basicity (salt formation with a hydrohalic acid) and one demonstrating its reducing power (precipitating a metal phosphide fro …

Giving two reactions of the same type (e.g. two combustion reactions) instead of illustrating two different aspects of …