The standard heat of combustion of propane is -2220.1 kJ / mol. The standard heat of vaporizati

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The standard heat of combustion of propane is -2220.1 kJ /...

The standard heat of combustion of propane is $-2220.1 \mathrm{~kJ} / \mathrm{mol}$. The standard heat of vaporization of liquid water is $44 \mathrm{~kJ} / \mathrm{mol}$. What is the $\Delta H^{\text {o }}$ of the reaction: $\mathrm{C}_{3} \mathrm{H}_{8}(\mathrm{~g})+5 \mathrm{O}_{2}(\mathrm{~g}) \rightarrow 3 \mathrm{CO}_{2}(\mathrm{~g})+4 \mathrm{H}_{2} \mathrm{O}(\mathrm{g}) ?$ (a) $-2220.1 \mathrm{~kJ}$ (b) $-2044.1 \mathrm{~kJ}$ (c) $-2396.1 \mathrm{~kJ}$ (d) $-2176.1 \mathrm{~kJ}$

The standard heat of combustion of propane is $-2220.1 \mathrm{~kJ} / \mathrm{mol}$. The standard heat of vaporization of liquid water is $44 \mathrm{~kJ} / \mathrm{mol}$. What is the $\Delta H^{\text {o }}$ of the reaction:
$\mathrm{C}_{3} \mathrm{H}_{8}(\mathrm{~g})+5 \mathrm{O}_{2}(\mathrm{~g}) \rightarrow 3 \mathrm{CO}_{2}(\mathrm{~g})+4 \mathrm{H}_{2} \mathrm{O}(\mathrm{g}) ?$
(a) $-2220.1 \mathrm{~kJ}$
(b) $-2044.1 \mathrm{~kJ}$
(c) $-2396.1 \mathrm{~kJ}$
(d) $-2176.1 \mathrm{~kJ}$

Key Concepts

Reaction Enthalpy Calculation

This concept involves modifying a known reaction enthalpy to account for additional energy changes, such as phase transitions. For the given reaction, the standard combustion enthalpy for propane involves the production of liquid water. To obtain the enthalpy when water is produced as a gas, the energy required to vaporize water (the heat of vaporization) must be added for each mole of water. This adjustment is essential for accurately determining the total enthalpy change for the reaction as it occurs under the specified conditions.

Standard Heat of Combustion

This represents the energy released when one mole of a substance completely reacts with oxygen under standard conditions. It is a key thermodynamic value that provides a baseline for calculating reaction energies, particularly in combustion reactions. In the context of this problem, the heat of combustion of propane is given and serves as the primary energy change when propane burns to form carbon dioxide and water in its typical (liquid) state.

Heat of Vaporization

The heat of vaporization is the amount of energy required to convert a substance from a liquid to a gaseous state at constant temperature and pressure. In this problem, the standard heat of vaporization for water is provided, which is necessary to adjust the reaction enthalpy because the combustion reaction here produces water as gas instead of the liquid state typically assumed in standard combustion data.

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