The heat of combustion of acetylene is 312 Kcal . If heat of formation of `CO_(2) & H_(2)O` are -94 & -68 Kcal respectively . Given that heat of atomisation of C& H are 150 & 50 Kcal respectively and C-H bond energy is 93 Kcal . Calculate `(DeltaH_(C=C))/(6)`

Explanation

`HC -= CH + (5)/(2) O_(2) to 2 CO_(2) + H_(2)O`
`Delta H_(c)^(@) (CH -= CH) = 2 Delta H_(f)^(@) (CO_(2)) + Delta H_(f)^(@) (H_(2)O) - Delta H_(f)^(@) (C_(2) H_(2)) - 312 = 2 xx (-94 .38) + (-68.38) - Delta H_(f)^(@) (C_(2) H_(2))`
`Delta H_(f)^(@) (C_(2) H_(2)) = 54.86`
`CH -= CH to 2 C (g) + 2H(g)`
`sum C -= C + 2 sum C - H = 2 Delta H_(f)^(@) C (g) + 2 Delta H_(f)^(@) H(g) - Delta H_(f)^(@) (CH -= CH) `
`sum C -= C + 2 xx 93.64 = 2 xx 150 + 2 xx (1)/(2) xx 103 - 54.86`
`implies sum C -= C = 160.86 kJ mol^(-1)`