Use graph paper and sketch the phase diagram of argon, Ar, from the following information: normal melting point, $-187^{\circ} \mathrm{C}$; normal boiling point, $-186^{\circ} \mathrm{C}$; triple point, $-189^{\circ} \mathrm{C}, 0.68$ atm; critical point, $-122^{\circ} \mathrm{C}, 48$ atm. Label each phase region on the diagram.

Liquid butane, $C_4H_{10}$, is stored in cylinders to be used as a fuel. Suppose 39.3 g of butane gas is removed from a cylinder. How much heat must be provided to vaporize this much gas? The heat of vaporization of butane is 21.3 kJ/mol.

The heat of vaporization of ammonia is $23.4 \mathrm{~kJ} / \mathrm{mol}$. How much heat is required to vaporize $1.00 \mathrm{~kg}$ of ammonia? How many grams of water at $0^{\circ} \mathrm{C}$ could be frozen to ice at $0^{\circ} \mathrm{C}$ by the evaporation of this amount of ammonia?

Argon has a normal boiling point of 87.2 Kand a melting point (at 1 atm) of 84.1 K. Its critical temperature is 150.8 K and its critical pressure is 48.3 atm. It has a triple point at 83.7 K and 0.68 atm. Sketch the phase diagram for argon. Which has the greater density, solid argon or liquid argon?

Part 1: Is it possible to add heat to a pure substance and not observe a temperature change? If so, provide examples. Describe, on a molecular level, what happens to the heat being added to a substance just before and during melting. Do any of these molecular changes cause a change in temperature? Part 2: Consider two pure substances with equal molar masses: substance $A$, having very strong intermolecular attractions, and substance B, having relatively weak intermolecular attractions. Draw two separate heating curves for 0.25-mol samples of substance $A$ and substance $B$ in going from the solid to the vapor state. You decide on the freezing point and boiling point for each substance, keeping in mind the information provided in this problem. Here is some additional information for constructing the curves. In both cases, the rate at which you add heat is the same. Prior to heating, both substances are at $-50^{\circ} \mathrm{C}$, which is below their freezing points. The heat capacities of $\mathbf{A}$ and $\mathbf{B}$ are very similar in all states.

a. As you were heating substances $\mathrm{A}$ and $\mathrm{B}$, did they melt after equal quantities of heat were added to each substance? Explain how your heating curves support your answer. b. What were the boiling points you assigned to the substances? Are the boiling points the same? If not, explain how you decided to display them on your curves. c. According to your heating curves, which substance reached the boiling point first? Justify your answer. d. Is the quantity of heat added to melt substance $\mathrm{A}$ at its melting point the same as the quantity of heat required to convert all of substance $A$ to a gas at its boiling point? Should these quantities be equal? Explain.

Carbon disulfide, $\mathrm{CS}_2$, is a volatile, flammable liquid. It has a vapor pressure of $400.0 \mathrm{mmHg}$ at $28.0^{\circ} \mathrm{C}$ and $760.0 \mathrm{mmHg}$ at $46.5^{\circ} \mathrm{C}$. What is the heat of vaporization of this substance?

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?

Use graph paper and sketch the phase diagram of oxygen, $\mathrm{O}_2$, from the following information: normal melting point, $-218^{\circ} \mathrm{C}$; normal boiling point, $-183^{\circ} \mathrm{C}$; triple point, $-219^{\circ} \mathrm{C}, 1.10 \mathrm{mmHg}$; critical point, $-118^{\circ} \mathrm{C}$, $50.1 \mathrm{~atm}$. Label each phase region on the diagram.

Showa here is the phase diagram for compound $\mathrm{Z}$. The triple point of $\mathrm{Z}$ is $-5.1^{\circ} \mathrm{C}$ at $3.3$ atm and the critical point is $51^{\circ} \mathrm{C}$ and $99.1 \mathrm{~atm}$.

a. What is the state of $\mathrm{Z}$ at position $\mathrm{A}$ ?

b. If we increase the temperature of the compound at position $\mathrm{A}$ to $60 \Omega \mathrm{C}$ while holding the pressure constant, what is the state of $\mathrm{Z}$ ?

c. If we take the compound starting under the conditions of part b and reduce the temperature to $20^{\circ} \mathrm{C}$ and increase the pressure to $65 \mathrm{~atm}$, what is the state of $\mathrm{Z}$ ?

d. Would it be possible to make the compound a solid by starting with the conditions of part $\mathrm{c}$ and increasing just the pressure?

An automobile antifreeze solution contains 2.50 kg of ethylene glycol, $CH_2OHCH_2OH$, and 2.00 kg of water. Find the mole fraction of ethylene glycol in this solution. What is the mole fraction of water?

What is the freezing point of $0.0075 \mathrm{~m}$ aqueous calcium chloride, $\mathrm{CaCl}_2$ ? Use the formula of the salt to obtain $i$.