The bond dissociation enthalpy of X2 ΔHbond∘ calculated from the given data is _____ kJ mol-1. (Nearest integer)
M+X-(s)→M+(g)+X-(g) ΔHlattice∘=800 kJ mol-1
M(s)→M(g) ΔHsub∘=100 kJ mol-1
M(g)→M+(g)+e-(g) ΔHi∘=500 kJ mol-1
X(g)+e-(g)→X-(g) ΔHeg∘=-300 kJ mol-1
M(s)+12 X2(g)→M+X-(s) ΔHf∘=-400 kJ mol-1
[Given: M+X- is a pure ionic compound and X forms a diatomic molecule X2 in gaseous state] [2025]
(200)
ΔHf°=ΔHsub°+12ΔHbond°+ΔHi°+ΔHeg°-ΔHlattice°
-400=100+12ΔHbond°+500-300-800
ΔHbond°=200 kJ/mol