Question

the enthalpy of combustion of acetylene is -312 kCal per mole. If enthalpy of formation of `CO_(2)` & `H_(2)O` are `-94.38` & `-68.38` kCal per mole respectively, calculate `C equiv C` bond enthalpy.
given that enthalpy of atomisation of C is 150 kCal per mole and `H-H` bond enthlpy and `C-H` bond enthalpy are 103 kcal per mole and 93.64 kCal per mole respectively.

Answer 1

Correct Answer - `E_(C equiv C)= 160.86` kCal/mol
Enthalpy of formation of `C_(2)H_(2)=54.92`
`2 C(s)+H_(2) rarr HC equiv C-H`
`54.92=403-187.28-x" "[x=B.E." of "C equiv C]`
`x=160.86" kCal/mol"`