CHM161-02 Exam 3Name___________________________________ MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

1)

Which transformation is condensation?

1)

_______ A)

gas → liquid B)

solid → gas C)

solid → liquid D)

liquid → gas E)

liquid → solid

2)

Which process is exothermic?

2)

_______ A)

solid → gas B)

gas → liquid C)

liquid → gas D)

solid → liquid E)

none of the above

3)

Which of the assumptions of the kinetic-molecular theory best explains the observation that a gas can be compressed?

3)

_______ A)

Gas molecules move at random with no attractive forces between them. B)

Collisions with the walls of the container or with other molecules are elastic. C)

The amount of space occupied by a gas is much greater than the space occupied by the actual gas molecules.

D)

In collisions with the walls of the container or with other molecules, energy is conserved. E)

The velocity of gas molecules is proportional to their Kelvin temperature.

4)

Which of the assumptions of the kinetic-molecular theory best explains the observation that a balloon collapses when exposed to liquid nitrogen (which is much colder than a cold winter day!!)?

4)

_______ A)

The velocity of gas molecules is proportional to their Kelvin temperature. B)

The amount of space occupied by a gas is much greater than the space occupied by the actual gas molecules.

C)

In collisions with the walls of the container or with other molecules, energy is conserved. D)

Gas molecules move at random with no attractive forces between them. E)

Collisions with the walls of the container or with other molecules are elastic.

5)

Most gases show variations from ideality at ________ pressure and ________ temperature.

5)

_______ A)

moderate; moderate B)

high; high C)

low; high D)

low; low E)

high; low

6)

Volume and pressure are ________ proportional.

6)

_______ A)

directly

B)

inversely C)

all of the above

D)

none of the above

7)

What would be the new pressure if a 400 mL gas sample at 380 mm Hg is expanded to 800 mL with no change in temperature?

7)

_______ A)

190 mm Hg B)

570 mm Hg C)

380 mm Hg D)

950 mm Hg E)

760 mm Hg

8)

A sample of gas has a volume of 135 mL at 0.600 atm. What would be the volume if the pressure is decreased to 0.200 atm while temperature is held constant?

8)

_______ A)

180 mL

B)

405 mL

C)

45.0 mL

D)

135 mL

E)

101 mL

9)

A sealed container with gas at 2.00 atm is heated from 20.0 K to 40.0 K. The new pressure is

9)

_______ A)

4.00 atm.

B)

2.14 atm.

C)

1.87 atm.

D)

1.00 atm.

E)

0.500 atm.

10)

If the temperature of a 1.75 liter sample of gas is changed from 30.0°C to 20.0°C at constant pressure, what will be the new volume?

10)

______ A)

1.17 L

B)

2.63 L

C)

1.81 L

D)

1.57 L

E)

1.69 L

11)

A 250. mL sample of gas at 1.00 atm and 20.0°C has the temperature increased to 40.0°C and the volume increased to 500. mL. What is the new pressure?

11)

______ A)

0.374 atm

B)

0.468 atm

C)

1.87 atm

D)

2.14 atm

E)

0.534 atm

12)

How many moles of gas are present in a 10.0 liter sample at STP?

12)

______ A)

22.4 moles B)

10.0 moles C)

2.24 moles D)

0.446 moles E)

224 moles

13)

A sample of CO2 gas at 100.°C has a volume of 250. mL at 760. mm Hg. How many moles of CO2 are present?

13)

______ A)

0.00816 mol B)

23.14 mol C)

8.16 mol D)

0.0304 mol E)

6.20 mol

14)

Calculate the volume of a 3.50 mol sample of carbon dioxide at 30.0°C and 0.900 atm.

14)

______ A)

421 L B)

2.20 L C)

96.7 L D)

8.54 × 10-4 L E)

9.58 L

15)

What is the total pressure of a mixture of He and H2 if the partial pressures are 320 mm Hg and 800 mm Hg respectively?

15)

______ A)

480 mm Hg B)

40 mm Hg C)

1120 mm Hg D)

60 mm Hg E)

320 mm Hg

16)

In a gas mixture of 35% He and 65% O2 the total pressure is 800 mm Hg. What is the partial pressure of O2?

16)

______ A)

100 mm Hg B)

35 mm Hg C)

520 mm Hg D)

65 mm Hg E)

280 mm Hg

17)

The total pressure of a mixture of gases is:

17)

______ A)

the product of the individual pressures. B)

obtained by multiplying the individual pressures by the number of moles and averaging. C)

the sum of the partial pressures of the components D)

dependent only upon the pressure of the gas which is present to the greatest extent. E)

none of these.

18)

Which pair of molecules has the strongest dipole-dipole interactions?

18)

______ A)

CO2 and CO2 B)

NH3 and NH3 C)

CO2 and CH4 D)

NH3 and CH4 E)

CH4 and CH4

19)

Which intermolecular force is characteristic of compounds with low molar mass, which are liquids at room temperature and have relatively high boiling points?

19)

______ A)

hydrogen bonds B)

covalent bonds C)

london forces D)

dipole-dipole forces E)

ionic bonds

20)

Which is the best description of hydrogen bonding?

20)

______ A)

The association between hydrogen of one molecule and a region of another molecule which has become negative due to temporary shifts in electron density

B)

The association between a hydrogen atom which is somewhat positive because it is bonded to a small electronegative atom and an atom of O, N or F on another molecule

C)

The temporary attraction between hydrogen atoms on different molecules resulting from shifts in electron density

D)

The unique chemical bonds between hydrogen and any other atom in the same molecule E)

The polarity associated with a bond between hydrogen and a small electronegative atom to which it is bonded

21)

Which of the following cannot have hydrogen bonds?

21)

______ A)

H2O

B)

HCl

C)

CH3NH2

D)

NH3

E)

HF

22)

At a high altitude water boils at 95°C instead of 100°C as at sea level because

22)

______ A)

the climate is cooler. B)

the vapor pressure of water is less. C)

the atmospheric pressure is less. D)

the vapor pressure of water is greater. E)

the atmospheric pressure is greater.

23)

A solid compound which has no definite crystalline structure and a poorly defined melting point is referred to as a(an) ________ solid.

23)

______ A)

molecular B)

ionic C)

network covalent D)

amorphous E)

metallic

24)

The amount of energy involved in melting a substance without changing its temperature is called the

24)

______ A)

calorie. B)

heat of vaporization. C)

heat of combustion. D)

heat of fusion. E)

joule.

25)

The amount of energy associated with changing a liquid into a gas is called the

25)

______ A)

heat of vaporization. B)

heat of combustion. C)

heat of fusion. D)

calorie. E)

joule.

26)

In a mixture of 5 mL water, 10 mL alcohol, and 50 mL acetone the solvent(s) is(are) ________.

26)

______ A)

acetone B)

acetone and alcohol C)

alcohol D)

alcohol and water E)

water

27)

Which statement best explains the meaning of the phrase "like dissolves like"?

27)

______ A)

The only true solutions are formed when water dissolves a non-polar solute. B)

The only true solutions are formed when water dissolves a polar solute. C)

A solvent will easily dissolve a solute of similar mass. D)

A solvent and solute with similar intermolecular forces will readily form a solution. E)

None of these statements is correct.

28)

An ionic compounded that attracts atmospheric water strongly is said to be

28)

______ A)

soluble. B)

diluted. C)

immiscible. D)

miscible. E)

hygroscopic.

29)

The solubility of gases in liquids

29)

______ A)

decreases as temperature increases and increases as pressure increases. B)

increases as temperature increases and increases as pressure increases. C)

decreases as temperature increases and decreases as pressure increases. D)

increases as temperature increases and decreases as pressure increases. E)

is independent of temperature and increases as pressure increases.

30)

All of the statements about molarity are correct except

30)

______ A)

the molarity of a diluted solution is less than the molarity of the original solution. B)

the interpretation of the symbol is "moles of solute per mole of solvent." C)

moles = molarity × volume . D)

volume = moles/molarity. E)

the abbreviation is M.

31)

How many grams of NaOH are needed to make 750 mL of a 2.5% (w/v) solution?

31)

______ A)

50 g

B)

3.9 g

C)

20 g

D)

19 g

E)

7.5 g

32)

What is the % (w/v) concentration of a solution containing 12 grams of solute in 400 mL of solution?

32)

______ A)

4.0%

B)

3.0%

C)

1.2%

D)

12%

E)

6.0%

33)

What is the % (w/v) concentration of a solution containing 25.0 g of solute in 400. mL of solution?

33)

______ A)

12.5%

B)

2.50%

C)

5.00%

D)

6.25%

E)

25.0%

34)

Which solution is the most concentrated? Each choice refers to the same solute and solvent.

34)

______ A)

50 g solute in 175 mL solution B)

2.4 g solute in 2 mL solution C)

20 g solute in 50 mL solution D)

2.4 g solute in 5 mL solution E)

30 g solute in 150 mL solution

35)

What is the molarity of a solution prepared by dissolving 3.50 mol NaCl in enough water to make 1.50 L of solution?

35)

______ A)

5.25 M

B)

0.429 M

C)

87.8 M

D)

137 M

E)

2.33 M

36)

What is the molarity of a solution prepared by dissolving 48.0 g of NaOH in enough water to make 1.50 L of solution?

36)

______ A)

32.0 M

B)

1.28 M

C)

0.556 M

D)

0.800 M

E)

0.0313 M

37)

How many moles of HCl are present in 75.0 mL of a 0.200 M solution?

37)

______ A)

0.275 mol B)

15.0 mol C)

2.67 mol D)

0.375 mol E)

0.0150 mol

38)

A 50.0 mL sample of a 6.0 M solution of HCl is diluted to 200. mL. What is the new concentration?

38)

______ A)

1.50 M

B)

6.0 M

C)

24.0 M

D)

2.00 M

E)

2.10 M

39)

Which substance is not an electrolyte?

39)

______ A)

HCl

B)

CH4

C)

NH4NO3

D)

KOH

E)

NaCl

40)

The passage of a solvent across a semipermeable membrane because of concentration differences is called

40)

______ A)

dialysis.

B)

hemolysis.

C)

solvation.

D)

hydration.

E)

osmosis.