The heat of atomisation of PH_(3)(g) and P_(2)H_(4)(g) are 954 kJ"mol"^(-1) and 1485 kJ"mol"^(-1) respectively. The P - P bond energy in kJ"mol"^(-1) is

The heat of atomisation of PH_(3)(g) and P_(2)H_(4)(g) are 954 kJ"mol"

1.	The heat of atomisation of PH_(3)(g) and P_(2)H_(4)(g) are 954 kJ"mol"^(-1) and 1485 kJ"mol"^(-1) respectively. The P - P bond energy in kJ"mol"^(-1) is
Answer» 213 426 318 1272 Solution :`PH(3)(g) to P(g) + 3H(g) Delta_(r)H^(@) = 954 kJ"mol"^(-1)` The bond energy is the average energy for 3 P-H bonds as : Average bond energy pf P-H bond = `(954)/(3) = 318 kJ"mol"^(-1)` `P_(2)H_(4)` has four P-H bonds and ONE P-P bond B.E (P-P) + 4 B.E(P-H) = `1485 kJ"mol"^(-1)` B.E(P-P) + `4 xx 318 = 1485 kJ"mol"^(-1)` B.E(p-p) = `1485 - 4 xx 318` `= 1485 - 1272` =`213 kJ "mol"^(-1)`.