Chemical thermodynamics

Bond energy

Exercise 3

     

Use the →   Table of bond energies to calculate the standard enthalpy of the hydrogenation (addition of hydrogen) of cyanhydric acid ($HCN$) to méthanamine ($CH_5N$) .

$HC≡N(g)$ $ +$ $2H-H(g)$ $\longrightarrow$ $CH_3NH_2(g)$ $\Delta H $ $=$ $ E_{bond}(C-H)$ $ +$ $ E_{bond}(C≡N)$ $ - $ $(3E_{bond}(C-H)$ $+$ $E_{bond}(C-N)$ $+$ $2E_{bond}(N-H))$ $=$ $ -1020\;kJ$