The hydrogenation of ethene is represented by C_2H_4(g)+H_2(g) ; ;C_2H_6(g) Average…

CHEMISTRY · Single correct · A Level · Chemistry · Energetics · Energetics

Problem

The hydrogenation of ethene is represented by

\mathrm{C_2H_4(g)+H_2(g)\;\rightarrow\;C_2H_6(g)}

Average bond energies: C=C (614 kJ mol

^{-1}

), C–C (348 kJ mol

^{-1}

), C–H (413 kJ mol

^{-1}

), H–H (104 kcal mol

^{-1}

). (1 kcal = 4.184 kJ.) Calculate

\Delta H_{\mathrm{rxn}}

in kJ for the reaction as written. (a)

+125\ \text{kJ}

(b)

-456\ \text{kJ}

(c)

-125\ \text{kJ}

(d)

-44\ \text{kJ}