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Chapter 10: Problem 13

Explain the meanings of \(H, \Delta H,\) and \(\Delta H_{f}^{o}\)

Short Answer

Expert verified
Enthalpy (\(H\)) is the sum of internal energy and the product of pressure and volume of a system. Change in enthalpy (\(\Delta H\)) is the heat absorbed or released by a system at a constant pressure. \(\Delta H_{f}^{o}\) is the standard enthalpy of formation, it means the enthalpy change for the formation of one mole of the substance from its constituent elements in their standard states.

Step by step solution

01

Definition of Enthalpy, \(H\)

Enthalpy, denoted by \(H\), is a state function that combines the internal energy of a system with the product of its pressure and volume. It's a thermodynamic potential that measures the maximum amount of work that can be accomplished by a system at constant pressure.
02

Meaning of Change in Enthalpy, \(\Delta H\)

Change in Enthalpy, represented as \(\Delta H\), is the heat absorbed or released by a system in a process happening at constant pressure. It's calculated by subtracting the initial enthalpy (H-initial) from the final enthalpy (H-final), \(\Delta H = H_{\mathrm{final}} - H_{\mathrm{initial}}\). A positive \(\Delta H\) indicates an endothermic process (heat absorbed), while a negative \(\Delta H\) indicates an exothermic process (heat released).
03

Understanding Enthalpy of Formation, \(\Delta H_{f}^{o}\)

Standard Enthalpy of Formation, \(\Delta H_{f}^{o}\), is the change in Enthalpy during the formation of 1 mole of a substance from its constituent elements, with all substances in their standard states at 1 bar (or 1 atmosphere). This is a standard reference point for all substances.

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Most popular questions from this chapter

You need 70.2 \(\mathrm{J}\) to raise the temperature of 34.0 \(\mathrm{g}\) of ammonia, \(\mathrm{NH}_{3}(g),\) from \(23.0^{\circ} \mathrm{C}\) to \(24.0^{\circ} \mathrm{C}\) . Calculate the molar heat capacity of ammonia.

Why are the specific heats of \(\mathrm{F}_{2}(g)\) and \(\mathrm{Br}_{2}(g)\) very different, whereas their molar heat capacities are very similar?

Predict whether \(\Delta S\) is positive or negative for the following reaction. $$\mathrm{Ag}^{+}(a q)+\mathrm{Cl}^{-}(a q) \rightarrow \mathrm{AgCl}(s)$$

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