A quantity of $0.020$ mole of a gas initially at $0.050 \mathrm{~L}$ and $20^{\circ} \mathrm{C}$ undergoes a constant-temperature expansion until its volume is $0.50 \mathrm{~L}$. Calculate the work done (in joules) by the gas if it expands
If the gas in (b) is allowed to expand unchecked until its pressure is equal to the external pressure, what would its final volume be before it stopped expanding, and what would be the work done?

Ice at 0 °C is placed in a Styrofoam cup containing 361 g of a soft drink at 23 °C. The specific heat of the drink is about the same as that of water. Some ice remains after the ice and soft drink reach an equilibrium temperature of 0 °C. Determine the mass of ice that has melted. Ignore the heat capacity of the cup. (Hint: It takes 334 J to melt 1 g of ice of 0 °C.)

The standard enthalpy change $\Delta H°$ for the thermal decomposition of silver nitrate according to the following equation is +78.67 kJ:

$$\begin{align*} \mathrm{AgNO_3}(s)&\rightarrow\mathrm{AgNO_2}(s)+\dfrac{1}{2}\;\mathrm{O_2}(g) \end{align*}$$

The standard enthalpy of formation of $\mathrm{AgNO_3}(s)$ is -123.02 kJ/mol. Calculate the standard enthalpy of formation of $\mathrm{AgNO_2}(s)$.

Calculate the amount of heat liberated (in kJ) from 366 g of mercury when it cools from 77.0 °C to 12.0 °C.

Calculate the heats of combustion for the following reactions from the standard enthalpies of formation listed in Appendix 2: (a) $2\;\mathrm{H_2}(g)+\mathrm{O_2}(g) \rightarrow2\;\mathrm{H_2O}(l)$ (b) $2\;\mathrm{C_2H_2}(g)+5\;\mathrm{O_2}(g) \rightarrow4\;\mathrm{CO_2}(g)+2\;\mathrm{H_2O}(l)$

Describe hydration. What properties of water enable its molecules to interact with ions in solution ?

A 0.1375-g sample of solid magnesium is burned in a constant-volume bomb calorimeter that has a heat capacity of 3024 J/°C. The temperature increases by 1.126 °C. Calculate the heat given off by the burning Mg, in kJ/g and in kJ/mol.

A gas expands in volume from 26.7 to 89.3 mL at constant temperature. Calculate the work done (in joules) if the gas expands (a) against a vacuum, (b) against a constant pressure of 1.5 atm, and (c) against a constant pressure of 2.8 atm. $\left(1\;\mathrm{L\cdot atm}=101.3\;\mathrm{J}\right)$

A reaction having a 90 percent yield may be considered a successful experiment. However, in the synthesis of complex molecules such as chlorophyll and many anticancer drugs, a chemist often has to carry out multiple-step syntheses. What is the overall percent yield for such a synthesis, assuming it is a 30-step reaction with a 90 percent yield at each step?

For a glass fiber–epoxy matrix combination, the critical ratio of fiber length to fiber diameter is 40. Determine the fiber–matrix bond strength.

A quantity of $0.020$ mole of a gas initially at $0.050 \mathrm{~L}$ and $20^{\circ} \mathrm{C}$ undergoes a constant-temperature expansion until its volume is $0.50 \mathrm{~L}$. Calculate the work done (in joules) by the gas if it expands
against a constant pressure of $0.20$ bar.

A 1.00-mole sample of ammonia at $14.0$ bar and $25^{\circ} \mathrm{C}$ in a cylinder fitted with a movable piston expands against a constant external pressure of $1.00$ bar. At equilibrium, the pressure and volume of the gas are $1.00$ bar and $23.5 \mathrm{~L}$, respectively.
Calculate the final temperature of the sample.

The molar enthalpy of vaporization of a liquid $\left(\Delta H_{\text {vap }}\right)$ is the energy required to vaporize $1.00 \mathrm{~mol}$ of the liquid. In one experiment, $60.0 \mathrm{~g}$ of liquid nitrogen (boiling point $-196^{\circ} \mathrm{C}$ ) is poured into a Styrofoam cup containing $2.00 \times 10^2 \mathrm{~g}$ of water at $55.3^{\circ} \mathrm{C}$. Calculate the molar enthalpy of vaporization of liquid nitrogen if the final temperature of the water is $41.0^{\circ} \mathrm{C}$.

Producer gas (carbon monoxide) is prepared by passing air over red-hot coke:

$$\mathrm{C}(\mathrm{s})+\frac{1}{2} \mathrm{O}_2(\mathrm{~g}) \longrightarrow \mathrm{CO}(\mathrm{g})$$

Water gas (a mixture of carbon monoxide and hydrogen) is prepared by passing steam over redhot coke:

$$\mathrm{C}(\mathrm{s})+\mathrm{H}_2 \mathrm{O}(\mathrm{g}) \longrightarrow \mathrm{CO}(\mathrm{g})+\mathrm{H}_2(\mathrm{~g})$$

For many years, both producer gas and water gas were used as fuels in industry and for domestic cooking. The large-scale preparation of these gases was carried out alternately, that is, first producer gas, then water gas, and so on. Using thermochemical reasoning, explain why this procedure was chosen.