Notifications
Clear all
0
06/10/2020 4:50 pm
Topic starter
AB, A2 and B2 are diatomic molecules. If the bond enthalpies of A2, AB and B2 are in the ratio 1:1 :0.5 and enthalpy of formation of AB from A2 and B2 is –100 kJ mol-1. What is the bond energy of A2:
(a) 200 kJ mol-1
(b) 100 kJ mol-1
(c) 300 kJ mol-1
(d) 400 kJ mol-1
1 Answer
0
06/10/2020 4:54 pm
(d) 400 kJ mol-1
Explanation:
Let bond energy of A2 be x then bond energy of AB is also x and bond energy of B2 is x/2.
Enthalpy of formation of AB is -100 kJ/mole:
A2 + B2 → 2AB
1/2A2 + 1/2B2 → 2AB; ΔH = -100kJ
or - 100 = (1x/2 + x/4) - x
∴ -100 = (2x + x - 4x)/4
∴ x = 400 kJ mol-1