Question 1

A solution is prepared by dissolving 10.0 g of urea (molar mass = 60.06 g/mol) in 100.0 g of water. The freezing point depression constant for water is $$K_f = 1.86\ \mathrm{^\circ C\,kg\,$$mol^{-1}$$}$$ and the normal freezing point of water is $$0.00\ \mathrm{^\circ C}. $$What is the freezing point of the solution?

Accepted Answer

$$-1.86\ \mathrm{^\circ C}$$

Question 2

A 50.0 g sample of ice at $$-10.0\ \mathrm{^\circ C} is $$heated until it becomes steam at $$110.0\ \mathrm{^\circ C}. $$Given: $$\Delta H_{fus} = 6.01\ \mathrm{kJ/mol}$$, $$\Delta H_{vap} = 40.7\ \mathrm{kJ/mol}$$, $$c_{ice} = 2.09\ \mathrm{J/g\,^\circ C}$$, $$c_{water} = 4.18\ \mathrm{J/g\,^\circ C}$$, $$c_{steam} = 2.01\ \mathrm{J/g\,^\circ C}$$, and $$M_{H_2O} = 18.02\ \mathrm{g/mol}. $$What is the total energy required?

Accepted Answer

$$156.0\ \mathrm{kJ}$$

Question 3

A cubic unit cell contains 8 corner atoms and 1 atom at the center of the cell. What is the chemical formula for a compound if the corner atoms are sodium and the center atom is chlorine?

Accepted Answer

$$\mathrm{NaCl}$$

Question 4

The vapor pressure of ethanol at $$40.0\ \mathrm{^\circ C} is$$ $$150\ \mathrm{mmHg}. $$Given $$\Delta H_{vap} = 38.6\ \mathrm{kJ/mol}$$, what is the vapor pressure at $$60.0\ \mathrm{^\circ C}$$? (Use $$R = 8.314\ \mathrm{J/(mol\,K)})$$

Accepted Answer

$$450\ \mathrm{mmHg}$$

Question 5

Which of the following substances would have the highest surface tension at room temperature?

Accepted Answer

$$\mathrm{H_2O} ($$water)

Question 6

How does increasing temperature affect the viscosity of a typical liquid such as glycerol?

Accepted Answer

Viscosity decreases as temperature increases.

Question 7

Which solvent would best dissolve potassium iodide ($$\mathrm{KI}$$)?

Accepted Answer

Water ($$\mathrm{H_2O})$$

Question 8

Which of the following molecules would have the highest boiling point?

Accepted Answer

$$\mathrm{NH_3$}$$

Question 9

On a phase diagram, what does the point where all three phase boundaries meet represent?

Accepted Answer

The triple point

Question 10

If a substance is at its normal boiling point, what is the pressure?

Accepted Answer

$$1\ \mathrm{atm}$$

Question 11

A solution is made by dissolving 5.00 g of glucose ($$\mathrm{C_6H_{12}O_6$}$$, molar mass = 180.16 g/mol) in 100.0 g of water. What is the freezing point of the solution? ($$K_f = 1.86\ \mathrm{^\circ C\,kg\,$$mol^{-1}$$})$$

Accepted Answer

$$-0.52\ \mathrm{^\circ C}$$

Question 12

Which of the following compounds would have the lowest vapor pressure at room temperature?

Accepted Answer

$$\mathrm{H_2O} ($$water)

Question 13

Which of the following best describes the intermolecular forces present in $$\mathrm{CH_3F}$$?

Accepted Answer

Dipole-dipole and London dispersion forces

Question 14

Which of the following would increase the capillary action of water in a glass tube?

Accepted Answer

Increasing the strength of adhesion between water and glass

Question 15

A phase diagram shows a substance at high pressure and low temperature. Which phase is most likely present?

Accepted Answer

Solid

Question 16

Which of the following substances would be most soluble in hexane ($$\mathrm{C_6H_{14}}$$)?

Accepted Answer

Iodine ($$\mathrm{I_2$})$$

Question 17

Which of the following statements about the critical point on a phase diagram is correct?

Accepted Answer

It is the temperature and pressure above which the liquid and gas phases are indistinguishable.

Question 18

Which of the following molecules has only London dispersion forces as its intermolecular force?

Accepted Answer

$$\mathrm{CO_2$}$$

Question 19

A sample of water is heated from $$20.0\ \mathrm{^\circ C} to$$ $$120.0\ \mathrm{^\circ C}. $$How many phase changes occur and what are they?

Accepted Answer

One: vaporization

Question 20

Which of the following would have the lowest boiling point?

Accepted Answer

$$\mathrm{CH_4$}$$

CHE 140 Final Exam Study Guide: Liquids, Solids, and Intermolecular Forces

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