Question 11A.25: What happens when (i) (NH4)2Cr2O7 is heated? (ii) PCl5 is he......

(i) On heating (NH_4)_2Cr_2O_7, nitrogen gas is evolved.

\left( NH _4\right)_2 Cr _2 O _7 \xrightarrow{\text { Heat }} Cr _2 O _3+ N _2+4 H _2 O

(ii) On heating, PCl_5 first sublimes and then decomposes on strong heating :

PCl _5 \xrightarrow{\text { Heat }} PCl _3+ Cl _2

(iii) On heating, H_3PO_3 disproportionates to give orthophosphoric acid and phosphine.

\stackrel{+3}{4 H _3 PO _3} \longrightarrow \underset{\text{Orthophosphoric acid}}{\stackrel{+5}{3 H _3 PO _4}}+ \underset{\text{Phosphine}}{\stackrel{-3}{PH _3}}