At 300 K, the standard enthalpies of formation of C6 H5 COOH(s), CO,(g) and H2 O(s) are -408,-3

step 1 We are given that the benjoic acid which is C6H5 C O .O .H in solid state plus 15 by 2 o2 which

At 300 K, the standard enthalpies of formation of C6 H5...

At $300 \mathrm{~K}$, the standard enthalpies of formation of $\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{COOH}(\mathrm{s}), \mathrm{CO},(\mathrm{g})$ and $\mathrm{H}_{2} \mathrm{O}(\mathrm{s})$ are $-408,-393$ and $-286 \mathrm{~kJ} \mathrm{~mol}^{-1}$ respectively. Calculate the heat of combustion of benzoic acid at constant volume. (a) $-3296 \mathrm{~kJ} \mathrm{~mol}^{-1}$ (b) $-3200 \mathrm{~kJ} \mathrm{~mol}^{-1}$ (c) $-3201 \mathrm{~kJ} \mathrm{~mol}^{-1}$ (d) $-3603 \mathrm{~kJ} \mathrm{~mol}^{-1}$

At $300 \mathrm{~K}$, the standard enthalpies of formation of $\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{COOH}(\mathrm{s}), \mathrm{CO},(\mathrm{g})$ and $\mathrm{H}_{2} \mathrm{O}(\mathrm{s})$ are $-408,-393$
and $-286 \mathrm{~kJ} \mathrm{~mol}^{-1}$ respectively. Calculate the heat of combustion of benzoic acid at constant volume.
(a) $-3296 \mathrm{~kJ} \mathrm{~mol}^{-1}$
(b) $-3200 \mathrm{~kJ} \mathrm{~mol}^{-1}$
(c) $-3201 \mathrm{~kJ} \mathrm{~mol}^{-1}$
(d) $-3603 \mathrm{~kJ} \mathrm{~mol}^{-1}$

Key Concepts

Combustion Reaction

Combustion reactions are exothermic processes where a substance reacts with oxygen to produce combustion products, typically carbon dioxide and water, while releasing heat. The heat of combustion quantifies the energy released during this reaction, which is an important parameter in energy production and fuel efficiency assessments.

Standard Enthalpy of Formation

This is the enthalpy change when one mole of a compound is formed from its constituent elements in their standard states under specified conditions, typically at 1 atm and 25°C. It is used as a reference to calculate the enthalpy change for other reactions, such as combustion, by providing a baseline energy for the substances involved.

Hess's Law

Hess's Law states that the total enthalpy change for a chemical reaction is the same regardless of the pathway between the initial and final conditions. This principle allows us to calculate reaction enthalpies by combining the standard enthalpies of formation of the reactants and products, effectively enabling the use of a series of steps whose individual enthalpy changes sum to the overall reaction enthalpy.

Constant Volume Conditions

Under constant volume conditions, such as in a bomb calorimeter, the measured energy change corresponds to the change in internal energy (?U) of the system. Unlike constant pressure processes where enthalpy (?H) is measured, constant volume measurements require careful interpretation to relate them to the heat released by a reaction.

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