Question

Using bond enthalpy data, calculate enthalpy of formation of isoprene.

Given: C – H = 98.8 k Cal; H – H = 104 k Cal;

C – C = 83 k Cal; C = C = 147 k Cal &

C(s) → C (g) = 171 k Cal 

Answer 1

= 5×171+[4×104–2×83–2×147–8×98.8] = 20.6 K cal