Question

Hydrogen, a potential future fuel, can be produced from carbon (from coal) and steam by the following reaction: C(s)+2H2O(g)→2H2(g)+CO2(g) Note that the average bond energy for the breaking of a bond in CO2 is 799 kJ/mol.

Answer 1

The question is incomplete , complete question is:

Hydrogen, a potential future fuel, can be produced from carbon (from coal) and steam by the following reaction:

$C(s)+ 2 H_2O(g)\rightarrow 2H_2(g)+CO_2(g).\Delta H=?$

Note that the average bond energy for the breaking of a bond in CO2 is 799 kJ/mol. Use average bond energies to calculate ΔH of reaction for this reaction.

Answer:

The ΔH of the reaction is -626 kJ/mol.

Explanation:

$C(s)+ 2 H_2O(g)\rightarrow 2H_2(g)+CO_2(g).\Delta H=?$

We are given with:

$\Delta H_{H-O}=459 kJ/mol$

$\Delta H_{H-H}=432 kJ/mol$

$\Delta H_{C=O}=799 kJ/mol$

ΔH =  (Energies required to break bonds on reactant side) - (Energies released on formation of bonds on product side)

$\Delta H=(4\times \Delta H_{O-H})-(2\times \Delta H_{H-H}+2\times\Delta H_{C=O})$

$=(4\times 459 kJ/mol)-(2\times 432 kJ/mol+2\times 799 kJ/mol$

$\Delta H=-626 kJ/mol$

The ΔH of the reaction is -626 kJ/mol.