Enthalpy, H

State the mathematical definition of enthalpy $\left(\mathrm{H}\right)$. Show that at a constant temperature $\left(\mathrm{T} \mathrm{K}\right)$, $∆\mathrm{H} = ∆\mathrm{U} +∆\mathrm{nRT}$, for a gaseous reaction where the gases obey the ideal gas law.

Give the appropriate reasons for the following: It is preferable to determine the change in enthalpy than change in internal energy.

Derive a relation between enthalpy change $\left(∆\mathrm{H}\right)$, internal energy $\left(∆\mathrm{U}\right)$ and temperature $\left(\mathrm{T}\right)$ for gaseous reactions.

Define enthalpy and enthalpy change.

The amount of heat exchanged with the surrounding at constant temperature and pressure is called:

Enthalpy is _____ function.

The enthalpy change for the reaction is $\left(∆\mathrm{H}\right)$ for the reaction is $-92.38 \mathrm{kJ}$at $298 \mathrm{K}$. What is the value of $∆\mathrm{U}$ at $298 \mathrm{K}$.

${\mathrm{N}}_2\left(\mathrm{g}\right) + 3{\mathrm{H}}_2\left(\mathrm{g}\right) \to 2{\mathrm{NH}}_3\left(\mathrm{g}\right)$

One molecule of naphthalene $\left({\mathrm{C}}_{10}{\mathrm{H}}_8\right)$ was burnt in oxygen gas at constant volume to give carbon dioxide and liquid water at ${25}^{\mathrm{o}}\mathrm{C}$. The heat evolved was found to be $5139.0 \mathrm{kJ}$. Calculate the heat of the reaction at constant pressure $\left(\mathrm{R} = 8.314 {\mathrm{JK}}^{-1} {\mathrm{mol}}^{-1}\right)$.