Use the following standard enthalpies of atom combination to
$\Delta$ H_ac° H₂(g) = -435.30 kJ/mol_rxn $\Delta$ H_ac F₂(g) = -157.98 kJ/mol_rxn
$\Delta$ H_ac° N₂(g) = -945.41 kJ/mol_rxn $\Delta$ H_ac° C(s) = -716.68 kJ/mol_rxn
$\Delta$ H_ac° O₂(g) = -498.34 kJ/mol_rxn $\Delta$ H_ac° NH₃(g) = -1171.8 kJ/mol_rxn
$\Delta$ H_ac° H₂O(g) = -926.3 kJ/mol_rxn $\Delta$ H_ac° HF(g) = -567.7 kJ/mol_rxn
-How much heat is absorbed or evolved when just enough H₂(g) reacts with just enough F₂(g) to produce 0.200 mol of HF(g) ?

Question

Use the following standard enthalpies of atom combination to

\Delta

H_ac° H₂(g) = -435.30 kJ/mol_rxn

\Delta

H_ac F₂(g) = -157.98 kJ/mol_rxn

\Delta

H_ac° N₂(g) = -945.41 kJ/mol_rxn

\Delta

H_ac° C(s) = -716.68 kJ/mol_rxn

\Delta

H_ac° O₂(g) = -498.34 kJ/mol_rxn

\Delta

H_ac° NH₃(g) = -1171.8 kJ/mol_rxn

\Delta

H_ac° H₂O(g) = -926.3 kJ/mol_rxn

\Delta

H_ac° HF(g) = -567.7 kJ/mol_rxn
-How much heat is absorbed or evolved when just enough H₂(g) reacts with just enough F₂(g) to produce 0.200 mol of HF(g) ?

Quizplus · Accepted Answer

The reaction between $H_2O(g)$ and $F_2O(g)$ to produce $HF(g)$ involves breaking bonds in the reactants and forming new bonds in the product. The enthalpy change for the reaction can be calculated using the given standard enthalpies of atom combination ($\Delta H_f^{\circ}$). The overall enthalpy change ($\Delta H_{rxn}$) is the sum of the enthalpies of the products minus the sum of the enthalpies of the reactants. Given that $0.200 \, \text{mol}$ of $HF(g)$ is produced and the $\Delta H_f^{\circ}$ for $HF(g)$ is $-567.7 \, \text{kJ/mol}$, the total enthalpy change for producing $0.200 \, \text{mol}$ of $HF(g)$ is $0.200 \, \text{mol} \times -567.7 \, \text{kJ/mol} = -113.54 \, \text{kJ}$. Since the question asks for the heat absorbed or evolved when $H_2O(g)$ reacts with $F_2O(g)$, and given the enthalpies for $H_2O(g) = -926.3 \, \text{kJ/mol}$ and $F_2O(g) = -157.98 \, \text{kJ/mol}$, the net reaction involves the release of heat. The closest option to the calculated value, considering the enthalpy of formation and the stoichiometry of the reaction, is that 54 kJ of heat is evolved, indicating an exothermic reaction.

Use the Following Standard Enthalpies of Atom Combination To Δ\DeltaΔ Hac° H2(g) = -435

Use the Following Standard Enthalpies of Atom Combination To $\Delta$ H_ac° H₂(g) = -435