Given the standard heats of reaction

Reaction ∆H 0

M(s) + 2 X2(g) → MX4(g) −98.7 kJ/mol

X2(g) → 2 X(g) +327.3 kJ/mol

M(g) → M(s) −20.1 kJ/mol


calculate the average bond energy for a single

M-X bond.

Answer in units of kJ/mol.