Question

Using the bond enthalpy data given below, calculate the enthalpy change for the reaction  

C₂H₄ (g) +H₂ (g) → C₂H₆(g)

Data: 

Bond	C – C	C = C	C – H	H - H
Bond Enthalpy	336.81 kJ 1mol	606.68 kJ 1mol	410.87 kJ 1mol	431.79 kJ 1mol

Answer 1

C₂ H₄ (g) + H₂ (g) →C₂ H₆(g) 

∆H_reaction = ΣBE_reactants – ΣBE_products

= 1 × C = C + 4 × C–H – 1 × C – E + 6 × (–H)

= 1 × C = C – 1 × C–C = 2 × C–4

= 606.68 + 431.79 – 336 – 81 – 2 × 410.87

= –120.08