Steam at $100^{\circ} \mathrm{C}$ was passed into a flask containing $275 \mathrm{~g}$ of water at $21^{\circ} \mathrm{C}$, where the steam condensed. How many grams of steam must have condensed if the temperature of the water in the flask was raised to $83^{\circ} \mathrm{C}$ ? The heat of vaporization of water at $100^{\circ} \mathrm{C}$ is $40.7 \mathrm{~kJ} / \mathrm{mol}$ and the specific heat is $4.18 \mathrm{~J} /\left(\mathrm{g} \cdot{ }^{\circ} \mathrm{C}\right)$.

White phosphorus, $P_4$, is normally a white, waxy solid melting at $44^{\circ} \mathrm{C}$ to a colorless liquid. The liquid has a vapor pressure of $400.0 \mathrm{mmHg}$ at $251.0^{\circ} \mathrm{C}$ and $760.0 \mathrm{mmHg}$ at $280.0^{\circ} \mathrm{C}$. What is the heat of vaporization of this substance?

Methanol, $\mathrm{CH}_3 \mathrm{OH}$, a colorless, volatile liquid, was formerly known as wood alcohol. It boils at $65.0^{\circ} \mathrm{C}$ and has a heat of vaporization of $37.4 \mathrm{~kJ} / \mathrm{mol}$. What is its vapor pressure at $22.0^{\circ} \mathrm{C}$ ?

Chloroform, $\mathrm{CHCl}_3$, a volatile liquid, was once used as an anesthetic but has been replaced by safer compounds. Chloroform boils at $61.7^{\circ} \mathrm{C}$ and has a heat of vaporization of $31.4 \mathrm{~kJ} / \mathrm{mol}$. What is its vapor pressure at $36.2^{\circ} \mathrm{C}$ ?

If atoms of a metallic element react with atoms of a nonmetallic element, which element loses electrons and which element gains them?

A quantity of ice at $0^{\circ} \mathrm{C}$ is added to $64.3 \mathrm{~g}$ of water in a glass at $55^{\circ} \mathrm{C}$. After the ice melted, the temperature of the water in the glass was $15^{\circ} \mathrm{C}$. How much ice was added? The heat of fusion of water is $6.01 \mathrm{~kJ} / \mathrm{mol}$ and the specific heat is $4.18 \mathrm{~J} /\left(\mathrm{g} \cdot{ }^{\circ} \mathrm{C}\right)$.

Water at $0^{\circ} \mathrm{C}$ was placed in a dish inside a vessel maintained at low pressure by a vacuum pump. After a quantity of water had evaporated, the remainder froze. If $9.31 \mathrm{~g}$ of ice at $0^{\circ} \mathrm{C}$ was obtained, how much liquid water must have evaporated? The heat of fusion of water is $6.01 \mathrm{~kJ} / \mathrm{mol}$ and its heat of vaporization is $44.9 \mathrm{~kJ} / \mathrm{mol}$ at $0^{\circ} \mathrm{C}$.

Calculate the entropy change, $\Delta S^{\circ}$, for the vaporization of ethanol, $\mathrm{C}_2 \mathrm{H}_5 \mathrm{OH}$, at its normal boiling point, $78.0{ }^{\circ} \mathrm{C}$. The enthalpy of vaporization of ethanol is $39.3 \mathrm{~kJ} / \mathrm{mol}$.

Isopropyl alcohol, $\mathrm{CH}_3 \mathrm{CH} \mathrm{OH} \mathrm{CH}_3 \mathrm{CH}_3$ , is used in rubbing alco hol mixtures. Alco hol on the skin cools by evaporation . How much heat is absorbed by the alco hol if 2.25 g evaporates? The heat of vaporization of isopropyl alcohol is 42.1 kJ/mol.

A 35.8-g sample of cadmium metal was melted by an electric heater providing $4.66 \mathrm{~J} / \mathrm{s}$ of heat. If it took $6.92 \mathrm{~min}$ from the time the metal began to melt until it was completely melted, what is the heat of fusion per mole of cadmium?

Describe how you could liquefy the following gases: a. methyl chloride, $\mathrm{CH}_3 \mathrm{Cl}$ (critical point, $144^{\circ} \mathrm{C}$, 66 atm); b. oxygen, $\mathrm{O}_2$ (critical point, $-119^{\circ} \mathrm{C}, 50 \mathrm{~atm}$ ).

Explain why $15 \mathrm{~g}$ of steam at $100^{\circ} \mathrm{C}$ melts more ice than $15 \mathrm{~g}$ of liquid water at $100^{\circ} \mathrm{C}$.

Identify the phase transition occurring in each of the following.

a. Mothballs slowly become smaller and eventually disappear. b. Rubbing alcohol spilled on the palm of the hand feels cool as the volume of liquid decreases. c. A black deposit of tungsten metal collects on the inside of a lightbulb whose filament is tungsten metal. d. Raindrops hit a cold metal surface, which becomes covered with ice. e. Candle wax turns to liquid under the heat of the candle flame. 11.39 Use Figure $11.7$ to estimate the boiling point of diethyl ether, $\left(\mathrm{C}_2 \mathrm{H}_5\right)_2 \mathrm{O}$, under an external pressure of $350 \mathrm{mmHg}$.

Consider two flasks that contain different pure liquids at $20^{\circ} \mathrm{C}$

The liquid in one flask, substance $\mathrm{A}$, has a molar mass of $100 \mathrm{~g} / \mathrm{mol}$ and has hydrogen bonding. The liquid in the other flask, substance B, has a molar mass of $105 \mathrm{~g} / \mathrm{mol}$ and has dipole-dipole interactions. a.. If the molecular structures of the compounds are very similar, which flask probably contains substance $\mathbf{A}$ ? b. If you were to increase the temperature of each of the flasks by $15^{\circ} \mathrm{C}$, how would the pictures change (assume that you stay below the boiling points of the liquids)?