Question

Explain how changing the concentration The enthalpy change for the reaction, 3CO (g) 2Fe2O3 (s) Imported Asset Fe(s) 3CO2 (g), can be calculated from ΔHf values for each reactant and product. Which substance or substances in this equation have a ΔHf value equal to 0.0 kilojoules

Answer 1

Answer: For the given equation, only iron has the value of $\Delta H_f$ equal to 0 kJ.

Explanation:

Enthalpy change is defined as the difference in enthalpies of all the product and the reactants each multiplied with their respective number of moles. It is represented as $\Delta H^o$

The equation used to calculate enthalpy change is of a reaction is:

$\Delta H^o_{rxn}=\sum [n\times \Delta H^o_f(product)]-\sum [n\times \Delta H^o_f(reactant)]$

For the given chemical reaction:

$3CO(g)+2Fe_2O_3(s)\rightarrow Fe(s)+3CO_2(g)$

The equation for the enthalpy change of the above reaction is:

$\Delta H^o_{rxn}=[(1\times \Delta H^o_f_{(Fe(s))})+(3\times \Delta H^o_f_{(CO_2(g))})]-[(3\times \Delta H^o_f_{(CO(g))})+(2\times \Delta H^o_f_{(Fe_2O_3(s))})]$

The enthalpy of formation for the substances present in their elemental state is taken as 0.

Here, iron is present in its elemental state which is solid.

Hence, for the given equation, only iron has the value of $\Delta H_f$ equal to 0 kJ.