Chemical thermodynamics

Bond energy

Exercise 2

     

Use the →   Table of bond energies to calculate the combustion heat of $C_2H_2(g)$ ( to $CO_2(g)$ and $H_2O(g))$.

$H_2C=CH_2(g) +3O=O(g)$ $\longrightarrow$ $2 O=C=O (g)+2H-O-H(g)$ $\Delta H$ $=$ $4E_{bond}(C-H)$ $ + $ $E_{bond}(C=C)$ $ + $ $3E_{bond}(O=O)$ $- $ $(4E_{bond}(C=O)$ $+$ $4E_{bond}(H-O))$ $=$ $-930\; kJ$ $\Delta H_c(C_2H_4)$ $=$ $-930\;kJ$