1) A sample consisting of 1.00 mol of the molecules in air is expanded isothermally at 25°C from 24.2 dm^{3} to 48.4 dm^{3} (a) reversibly, (b) against a constant external pressure equal to the final pressure of the gas, and (c) freely (against zero external pressure). For the three processes calculate *q*, *w*, Δ*U*, and Δ*H*.

2) A sample of oxygen of mass 96 g at 25.0 °C is allowed to expand reversibly and adiabatically from 5.00 dm^{3} to 10.00 dm^{3}. What is the work done by the gas?

3) When 5.00 mol N_{2} is heated at a constant pressure of 3.00 atm, its temperature increases from 298 K to 345 K. Given that the molar heat capacity of N_{2} at constant pressure is 29.125 J K^{–1} mol^{–1}, calculate *q*, Δ*H*, and Δ*U.*

4) The standard enthalpy of combustion of n-propane (C_{3}H_{8}) is –2220 kJ mol^{–1} at 25 °C. From this information and enthalpy of formation data for CO_{2}(g) and H_{2}O(g), calculate the enthalpy of formation of n-propane. The enthalpy of formation of propene (C_{3}H_{6}) is +20.42 kJ mol^{–1}. Calculate the enthalpy of hydrogenation of propene to propane.

5) Benzoic Acid (C_{6}H_{5}COOH) is a commonly used standard used for determining the calorimeter constant of a bomb calorimeter. The enthalpy of combustion for benzoic acid is very well known and is found to be Δ_{c}H = -3227 kJ/mol. If a 0.596 g of benzoic acid is combusted in a bomb calorimeter and found to produce a 0.95 °C rise in temperature, calculate the calorimeter constant for the apparatus.

If 0.568 g of naphthalene (C_{10}H_{8}) is subsequently combusted in the bomb calorimeter at the same conditions, and produces a 1.56 °C rise in temperature, calculate the enthalpy of combustion of naphthalene.

6) A sample of nitrogen gas is adiabatically expanded such that its volume triples. If the sample initially is held 25 °C, what is the final temperature of the gas? Given that the initial pressure is 1 atm and the volume is 500 mL, calculate the work done.

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