An important step in the production of sulfuric acid is the...

An important step in the production of sulfuric acid is the oxidation of $\mathrm{SO}_{2}$ to $\mathrm{SO}_{3}$ $$ \mathrm{SO}_{2}(\mathrm{g})+1 / 2 \mathrm{O}_{2}(\mathrm{g}) \rightarrow \mathrm{SO}_{3}(\mathrm{g}) $$ Formation of $\mathrm{SO}_{3}$ from the air pollutant $\mathrm{SO}_{2}$ is also a key step in the formation of acid rain. (a) Use standard enthalpies of formation to calculate the enthalpy change for the reaction. Is the reaction exothermic or endothermic? (b) Draw an energy level diagram that shows the relationship between the enthalpy change for the oxidation of $\mathrm{SO}_{2}$ to $\mathrm{SO}_{3}$ and the enthalpies of formation of $\mathrm{SO}_{2}(\mathrm{g})$ and $\mathrm{SO}_{3}(\mathrm{g}).$

An important step in the production of sulfuric acid is the oxidation of $\mathrm{SO}_{2}$ to $\mathrm{SO}_{3}$
$$
\mathrm{SO}_{2}(\mathrm{g})+1 / 2 \mathrm{O}_{2}(\mathrm{g}) \rightarrow \mathrm{SO}_{3}(\mathrm{g})
$$
Formation of $\mathrm{SO}_{3}$ from the air pollutant $\mathrm{SO}_{2}$ is also a key step in the formation of acid rain.
(a) Use standard enthalpies of formation to calculate the enthalpy change for the reaction. Is the reaction exothermic or endothermic?
(b) Draw an energy level diagram that shows the relationship between the enthalpy change for the oxidation of $\mathrm{SO}_{2}$ to $\mathrm{SO}_{3}$ and the enthalpies of formation of $\mathrm{SO}_{2}(\mathrm{g})$ and $\mathrm{SO}_{3}(\mathrm{g}).$

Key Concepts

Energy Level Diagrams in Reaction Thermochemistry

Energy level diagrams provide a visual representation of the progressive energy changes during a chemical reaction. They depict the relative energy states of reactants and products, and illustrate the enthalpy change (?H) of the reaction, which is crucial for understanding the thermodynamic feasibility and the energy profile of chemical processes.

Exothermic and Endothermic Reactions

Exothermic reactions release heat to the surroundings, resulting in a negative enthalpy change, while endothermic reactions absorb heat, leading to a positive enthalpy change. Recognizing these types of reactions is essential for predicting reaction behavior and understanding energy transfer in chemical processes.

Standard Enthalpy of Formation

The standard enthalpy of formation is the heat change that occurs when one mole of a substance is formed from its elemental components in their standard states. This concept serves as the foundation for calculating reaction enthalpies and is critical for understanding how compounds form and their associated energy changes.

Hess's Law and Reaction Enthalpy Calculation

Hess's Law states that the overall enthalpy change for a chemical reaction is independent of the reaction pathway. This principle allows for the calculation of a reaction’s enthalpy change by summing the standard enthalpies of formation of products minus those of reactants, thereby determining whether the reaction is exothermic or endothermic.

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