[VoltarGomes]

Here is the question:

Phosphorus, P4(s), reacts with hot water to form phosphine, PH3(g), and phosphoric acid, H3PO4(aq). Write a balanced chemical reaction for this equation.

I’m trying to balance this using half reactions (adding H20 and H+) but am getting myself confused. Is this a disproportionation reaction where Phosphorus is both oxidized and reduced? Or is the H20 the second half reaction with the H3PO4?

[Borek]

Yes, it can be balanced as disproportionation.

Not that it is really necessary, P₄ + H₂O PH₃ + H₃PO₄ balances quite nicely (hint: start with oxygen, it is present in two molecules only).

[AWK]

(adding H20 and H+)

Your method works - just do it carefully - or show you result to get more help.