The standard enthalpy of formation (Delta_fH^ | vedclass

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(C) The standard enthalpy of formation of $CH_4$ is given by the reaction: $C_{(s)} + 2H_{2(g)} \rightarrow CH_{4(g)}$ To calculate the average $C-H$

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the dissociation energy of $H_2$ and enthalpy of sublimation of carbon

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(C) The standard enthalpy of formation of $CH_4$ is given by the reaction: $C_{(s)} + 2H_{2(g)} \rightarrow CH_{4(g)}$ To calculate the average $C-H$ bond energy,we need to consider the atomization of the reactants: $1.$ Enthalpy of sublimation of carbon: $C_{(s)} \rightarrow C_{(g)}$ $2.$ Dissociation energy of hydrogen: $2H_{2(g)} \rightarrow 4H_{(g)}$ By using Hess's Law,we combine these with the enthalpy of formation to find the total bond dissociation energy of $CH_4$,which is then divided by $4$ to get the average $C-H$ bond energy. Therefore,the dissociation energy of $H_2$ and the enthalpy of sublimation of carbon are required.

The standard enthalpy of formation $(\Delta_fH^o)$ at $298 \ K$ for methane,$CH_{4(g)}$ is $-74.8 \ kJ \ mol^{-1}$. The additional information required to determine the average energy for $C-H$ bond formation would be

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If the standard heat of the reaction $Fe_2O_{3(s)} + 3CO_{(g)} = 2Fe_{(s)} + 3CO_{2(g)}$ is $-6.6 \, kcal$,then $\Delta H_f^o$ for $Fe_2O_{3(s)}$ is $...... \, kcal/mol$. [Given: $\Delta H_f^o$ of $CO_{(g)} = -26.4 \, kcal$ and $\Delta H_f^o$ of $CO_{2(g)} = -94 \, kcal$]

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At $298 \, K$,the bond energies of $C-H, C-C, C=C$,and $H-H$ are $414, 347, 615$,and $435 \, kJ \, mol^{-1}$ respectively. What will be the enthalpy change for the reaction ${H_2}C=CH_{2(g)} + H_{2(g)} \to H_3C-CH_{3(g)}$ at $298 \, K$ in $kJ \, mol^{-1}$?

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