If the bond energies of H−H, Br−Br and H−Br are 433,192 and 364 kJ mol−1 respectively. Then ΔHo for the reaction H2(g)+Br2(g)→2HBr(g) is :
Use bond energies to estimate the enthalpy of formation of HBr(g). BE(H-H) = 436 kJ/mol BE(Br-Br) = 192 kJ/mol BE(H-Br) = 366 kJ/mol