Use the following themochemical equations to calculate the...

Use the following themochemical equations to calculate the standard enthalpy change of formation of $\mathrm{HNO}_{3}(0)$ \[ \begin{aligned} \mathrm{H}_{2} \mathrm{O}_{2}\left(\mathrm{D}+2 \mathrm{NO}_{2}(\mathrm{g}) \rightarrow 2 \mathrm{HNO}_{2}()\right.& \Delta_{4} H^{\circ} &=-226.8 \mathrm{kJ} \mathrm{mol}^{-1} \\ \mathrm{N}_{2}(\mathrm{g})+2 \mathrm{O}_{2}(\mathrm{g}) \rightarrow 2 \mathrm{NO}_{2}(\mathrm{g}) & \Delta_{\mathrm{r}} H^{\circ} &=+66.4 \mathrm{kJ} \mathrm{mol}^{-1} \\ \mathrm{H}_{2}(\mathrm{g})+\mathrm{O}_{2}(\mathrm{g}) \rightarrow \mathrm{H}_{2} \mathrm{O}_{2}(\mathrm{o}) & \Delta_{\mathrm{r}} \mathrm{H}^{\mathrm{e}} &=-187.8 \mathrm{kJ} \mathrm{mol}^{-1} \end{aligned} \] (Section $13.1)$

Use the following themochemical equations to calculate the standard enthalpy change of formation of $\mathrm{HNO}_{3}(0)$
\[
\begin{aligned}
\mathrm{H}_{2} \mathrm{O}_{2}\left(\mathrm{D}+2 \mathrm{NO}_{2}(\mathrm{g}) \rightarrow 2 \mathrm{HNO}_{2}()\right.& \Delta_{4} H^{\circ} &=-226.8 \mathrm{kJ} \mathrm{mol}^{-1} \\
\mathrm{N}_{2}(\mathrm{g})+2 \mathrm{O}_{2}(\mathrm{g}) \rightarrow 2 \mathrm{NO}_{2}(\mathrm{g}) & \Delta_{\mathrm{r}} H^{\circ} &=+66.4 \mathrm{kJ} \mathrm{mol}^{-1} \\
\mathrm{H}_{2}(\mathrm{g})+\mathrm{O}_{2}(\mathrm{g}) \rightarrow \mathrm{H}_{2} \mathrm{O}_{2}(\mathrm{o}) & \Delta_{\mathrm{r}} \mathrm{H}^{\mathrm{e}} &=-187.8 \mathrm{kJ} \mathrm{mol}^{-1}
\end{aligned}
\]
(Section $13.1)$

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Key Concepts

Hess's Law

Hess's Law is the principle that the total enthalpy change for a reaction is independent of the pathway between the initial and final states. This concept allows one to use known enthalpy changes of multiple steps to calculate the enthalpy change of an overall reaction by algebraically summing the individual steps.

Standard Enthalpy of Formation

The standard enthalpy of formation is defined as the change in enthalpy when one mole of a compound is formed from its constituent elements in their standard states. It serves as a reference value in thermochemistry for calculating the enthalpy changes of reactions.

Thermochemical Equations

Thermochemical equations are chemical equations that include the enthalpy change of the reaction. They are essential tools in thermodynamics because they provide a direct link between the stoichiometry of reactions and the heat energy involved, allowing for calculations of unknown enthalpy changes.

Reaction Manipulation

Reaction manipulation involves reversing, scaling, and combining thermochemical equations to derive a target reaction and its overall enthalpy change. By carefully adjusting the given equations according to the rules of stoichiometry and sign conventions, one can accurately compute the desired enthalpy change using Hess's Law.

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