Colligative Properties of Liquids - General Chemistry - Quiz, Exercises of Chemistry

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Section 1: Multiple Choice. Circle the letter that corresponds to the best answer to each question. Each question in this section is worth 5 points.

1. Convert 82.1 kPa to mm Hg.

a) 0.810 mm Hg b) 10.9 mm Hg c) 616 mm Hg d) 2.40 × 10^3 mm Hg e) 6.32 × 10 6 mm Hg

2. If the volume of a confined gas is quadrupled while its temperature remains constant, what change will be observed?

a) The pressure of the gas will decrease to 1/4 its original value. b) The pressure of the gas will quadruple. c) The density of the gas will decrease to 1/2 its original value. d) The average velocity of the molecules will quadruple. e) The average velocity of the molecules will double.

3. At constant temperature and number of molecules, the volume of a gas is inversely proportional to its ________.

a) pressure b) mass c) molar mass d) square root of molar mass e) velocity

4. How many atoms are contained within the unit cell of a face-centered cubic lattice?

a) 2 b) 4 c) 8 d) 12 e) 14

5. The normal boiling point is defined as

a) the temperature at which the vapor pressure of a liquid equals 1 atm. b) the pressure at which any liquid boils at 273.15 K. c) the temperature at which water always boils. d) the pressure of a gas when its temperature reaches 373.15 K. e) the temperature at which the enthalpy of vaporization equals 40.7 kJ/mol.

6. What is the coordination number of an atom in a face-centered cubic lattice?

a) 6 b) 8 c) 10 d) 12 e) 16

7. At constant temperature, 14.0 L of O 2 at 0.882 atm is compressed to 1.75 L. What is the final pressure of O 2?

a) 0.111 atm b) 0.142 atm c) 7.06 atm d) 21.6 atm e) 27.8 atm

8. A balloon is filled with He gas to a volume of 3.22 L at 32 °C. The balloon is placed in liquid nitrogen until its temperature reaches –132 °C. Assuming the pressure remains constant, what is the volume of the cooled balloon?

a) 0.628 L b) 0.781 L c) 1.24 L d) 1.49 L e) 6.96 L

9. Calculate the density (in g/L) of Kr at 308 K and 527 mm Hg.

a) 2.30 g/L b) 4.78 g/L c) 31.1 g/L d) 1.75 × 10^3 g/L e) 2.36 × 10 4 g/L

10. What volume of O 2 , measured at 364.4 K and 0.978 atm, will be produced by the decomposition of 4.88 g KClO 3? 2 KClO 3 (s) → 2 KCl(s) + 3 O 2 (g)

a) 0.305 L b) 1.22 L c) 1.83 L d) 24.0 L e) 37.4 L

11. Sodium crystallizes in a body-centered cubic unit cell. If the length of an edge of the unit cell is 430 pm, what is the atomic radius of a sodium atom?

a) 186 pm b) 304 pm c) 372 pm d) 430 pm e) 745 pm

12. At what temperature will 50 mL of a 0.738 m solution of ethylene glycol (C 2 H 6 O 2 ) in water begin to freeze?

a) -4.12 °C b) -2.75 °C c) -1.37 °C d) -0.857 °C e) -0.248 °C

a 2 ⋅a

body diag.

Section 2: Free Response. Show your work in order to receive full credit for each of these questions.

13. Name the largest type of intermolecular attractive forces that exist between molecules of the given materials. Each blank on this question is worth 1 point.

Kr PH 3

H 2 S and O 2 C 3 H 8 and Cl 2

SiCl (^4)

14. 6 pts. Aluminum crystallizes in a face-centered cubic unit cell. In addition, aluminum has an atomic radius of 143 pm. What is the density of aluminum?
15. 8 pts. If 4.00 g S 8 react with 4.25 L O 2 at 39 °C and 1.00 atm, what is the maximum mass of SO 3 produced? S 8 (s) + 12 O 2 (g) → 8 SO 3 (g)

H

C O

O

H H

C H

O

H 3 C

C CH (^3)

O

a

a

face diag.

16. 6 pts. Circle one in each of the following pairs that you would predict to have the higher boiling point:

(a) NH 3 PH 3 (b) CH 4 CCl 4

(c) CO 2 O 3 (d) NO N 2

(e) CH 3 -CH 2 -CH 2 -O-CH 3 CH 3 -CH 2 -O-H

(f)

H 3 C

C

H 2

C

H 2

C

H 2

C

H 2

C

H 2

CH 3

H 2 C

C

H 2

CH 2

H 2 C CH 2

C

H 2

C

H 2

17. 6 pts. A graduated syringe at 25 °C is filled with neon gas to a volume of 35.0 mL at 2. atm pressure. The gas is now heated to 70. °C while the pressure on the plunger is relaxed to 1.20 atm. What is the final volume after heating?

18. 6 pts. What is the freezing point of a solution containing 4.78 grams of naphthalene

(C 10 H 8 ) dissolved in 32.0 grams of chloroform (CHCl 3 )?

Physical Constants for Colligative Properties of Liquids

Solvent Normal Boiling Point [o^ C]

Kbp [o^ C/m] Normal Freezing Point [o^ C]

Kfp [o^ C/m]

water 100.00 +0.5121 0.0 -1. benzene 80.10 +2.53 5.50 -5. camphor 207.4 +5.611 179.75 -39. chloroform 61.70 +3.63 -63.5 -4. acetone 56.5 +1. CCl 4 76.8 +5.02 -22.8 -29. ethyl alcohol 78.4 +1. carbon disulfide 46.2 +2.34 -111.5 -3. ethyl ether 34.5 +2.02 -116.2 -1.