Use bond energies to estimate the enthalpy change for the reaction of one mole of CH₄ with chlorine gas to give CH₃Cl and hydrogen chloride.

CHA(g) + Cl₂(g) → CH₃CI + HCl(g)

BE(C-H) = 414 kJ/mol
BE(CCl) = 326 kJ/mol
BE(H-Cl) = 432 kJ/mol
BE(Cl-Cl) = 243 kJ/mol