Chapter 9 3 two of which contain different gases and one

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114) Three bulbs, two of which contain different gases and one of which is empty, are connected

as shown in drawing (a). Which drawing (b) – (d) best represents the system after the stopcocks

are opened and the system is allowed to come to equilibrium?

A) drawing (b)

B) drawing (c)

C) drawing (d)

115) Effusion of a 1:1 mixture of two gases, represented by unshaded and shaded spheres in the

diagram below, through a small pinhole produces the result shown below. The shaded spheres

have a molecular mass of 32 amu. Which gas molecules have the higher average speed and what

is the molecular mass of the unshaded molecules?

A) Unshaded molecules have higher average speed and molecular mass = 14 amu

B) Unshaded molecules have higher average speed and molecular mass = 21 amu

C) Unshaded molecules have lower average speed and molecular mass = 48 amu

D) Unshaded molecules have lower average speed and molecular mass = 72 amu

116) Effusion of a 1:1 mixture of two gases, represented by unshaded and shaded spheres in the

diagram below, through a small pinhole produces the result shown below. The shaded spheres

have a molecular mass of 20 amu. Which gas molecules have the higher average speed and what

is the molecular mass of the unshaded molecules?

A) Unshaded molecules have higher average speed and molecular mass = 14 amu

B) Unshaded molecules have higher average speed and molecular mass = 17 amu

C) Unshaded molecules have lower average speed and molecular mass = 24 amu

D) Unshaded molecules have lower average speed and molecular mass = 29 amu

9.2 Algorithmic Questions

1) What is the pressure in a gas container that is connected to an open-end U-tube manometer if

the pressure of the atmosphere is 742 torr and the level of mercury in the arm connected to the

container is 8.60 cm higher than the level of mercury open to the atmosphere?

A) 656 mm Hg

B) 733 mm Hg

C) 751 mm Hg

D) 828 mm Hg

2) If the pressure in a gas container that is connected to an open-end U-tube manometer is 116

kPa and the pressure of the atmosphere at the open end of the tube is 752 mm Hg, the level of

mercury in the tube will

A) be 118 mm higher in the arm open to the atmosphere.

B) be 118 mm higher in the arm connected to the gas cylinder.

C) be 870 mm higher in the arm open to the atmosphere.

D) be 870 mm higher in the arm connected to the gas cylinder.

3) A container filled with gas is connected to an open-end manometer that is filled with mineral

oil. The pressure in the gas container is 753 mm Hg and atmospheric pressure is 724 mm. How

high will the level rise in the manometer if the densities of Hg and mineral oil are 13.6 g/mL and

0.822 g/mL respectively?

A) 1.75 mm

B) 23.8 mm

C) 29.0 mm

D) 480 mm

4) A basketball is inflated to a pressure of 1.90 atm in a 24.0°C garage. What is the pressure of

the basketball outside where the temperature is -1.00°C?

A) 1.74 atm

B) 1.80 atm

C) 2.00 atm

D) 2.08 atm

5) A gas bottle contains 0.250 mol of gas at 730 mm Hg pressure. If the final pressure is 1.15

atm, how many moles of gas were added to the bottle?

A) 0.0262 mol

B) 0.0493 mol

C) 0.276 mol

D) 0.299 mol

6) The volume of 350. mL of gas at 25°C is decreased to 135 mL at constant pressure. What is

the final temperature of the gas?

A) -158°C

B) 9.6°C

C) 65°C

D) 500°C

7) A balloon filled with helium gas at 20 °C occupies 4.91 L at 1.00 atm. The balloon is

immersed in liquid nitrogen at -196°C, raising the pressure to 5.20 atm. What is the volume of

the balloon in the liquid nitrogen?

A) 0.25 L

B) 3.6 L

C) 6.7 L

D) 97 L

8) Three identical flasks contain three different gases at standard temperature and pressure. Flask

A contains flask B contains O3, and flask C contains F2. Which flask contains the largest

number of molecules?

A) flask A

B) flask B

C) flask C

D) All contain same number of molecules.

9) How many molecules of N2 are in a 400.0 mL container at 780 mm Hg and 135°C?

A) 7.01 × 1021 molecules

B) 7.38 × 1021 molecules

C) 2.12 × 1022 molecules

D) 2.23 × 1022 molecules

10) A 2.75-L container filled with CO2 gas at 25°C and 225 kPa pressure springs a leak. When

the container is re-sealed, the pressure is 185 kPA and the temperature is 10°C. How many moles

of gas were lost?

A) 0.0335 mol

B) 0.728 mol

C) 0.882 mol

D) 3.39 mol

11) A 45.0-L steel tank at 20.0°C contains acetylene gas, C2H2, at a pressure of 1.39 atm.

Assuming ideal behavior, how many grams of acetylene are in the tank?

A) 2.60 g

B) 10.0 g

C) 67.8 g

D) 990 g

12) A 4.00-L flask contains nitrogen gas at 25°C and 1.00 atm pressure. What is the final

pressure in the flask if an additional 2.00 g of N2 gas is added to the flask and the flask cooled to

-55°C?

A) 0.319 atm

B) 1.05 atm

C) 1.44 atm

D) 1.96 atm

13) A steel bottle contains argon gas at STP. What is the final pressure if the temperature is

changed to 145°C?

A) 0.653 atm

B) 0.713 atm

C) 1.40 atm

D) 1.53 atm

14) A gas occupies 22.4 L at STP and 19.0 L at 100°C and 1.50 atm pressure. How many moles

of gas did the system gain or lose?

A) 0.08 moles gained

B) 0.01 moles gained

C) 0.01 moles lost

D) 0.07 moles lost

15) How many grams of NO gas are there in a 5.00-L cylinder at 4.00 × 103 mm Hg and 23°C?

A) 13.9 g

B) 32.1 g

C) 417 g

D) 2.47 × 104 g

16) What is the volume of 30.0 g of argon gas at 157°C and 2.50 kPa pressure?

A) 3.87 L

B) 10.6 L

C) 393 L

D) 1070 L

17) What is the Celsius temperature of 100.0 g of chlorine gas in a 55.0-L container at 800 mm

Hg?

A) -23°C

B) 228°C

C) 250°C

D) 500°C

18) A 0.286-g sample of gas occupies 125 mL at 60. cm of Hg and 25°C. What is the molar mass

of the gas?

A) 5.9 g/mol

B) 44 g/mol

C) 59 g/mol

D) 71 g/mol

19) A compound is 7.74% hydrogen and 92.26% carbon by mass. At 100°C a 0.6883 g sample

of the gas occupies 250 mL when the presssure is 820 torr. What is the molecular formula for

this compound?

20) What is the density of hydrogen gas at STP?

A) 11.1 g/L

B) 0.0450 g/L

C) 0.0823 g/L

D) 0.0899 g/L

21) Which of the following would have a density of 1.37 g/L at 7.0°C and 0.987 atm?

A) N2

B) O2

C) Kr

D) Rn

22) Given three cylinders containing O2 gas at the same volume and pressure. Cylinder A is at –

15°C, cylinder B is at -5°F, cylinder C is at 255 K. Which cylinder contains the largest mass of

oxygen?

A) cylinder A

B) cylinder B

C) cylinder C

D) All cylinders contain the same mass of O2.

23) The action of some commercial drain cleaners is based on the following reaction:

2 NaOH(s) + 2 Al(s) + 6 H2O(l) → 2 NaAl(OH)4(s) + 3 H2(g)

What is the volume of H2 gas formed at STP when 6.32 g of Al reacts with excess NaOH?

A) 3.50 L

B) 5.25 L

C) 7.87 L

D) 8.59 L

24) How many liters of oxygen are needed to exactly react with 19.8 g of methane at STP?

CH4(g) + 2 O2(g) → CO2(g) + 2 H2O(l)

A) 13.9 L

B) 27.8 L

C) 55.5 L

D) 60.5 L

25) When 14.0 g of zinc metal reacts with excess HCl, how many liters of H2 gas are produced

at STP?

A) 0.208 L

B) 0.416 L

C) 4.80 L

D) 9.60 L

26) How many grams of XeF6 are required to react with 0.579 L of hydrogen gas at 6.46 atm

and 45°C in the reaction shown below?

XeF6(s) + 3 H2(g) → Xe(g) + 6 HF(g)

A) 9.58 g

B) 11.7 g

C) 35.2 g

D) 106 g

27) A balloon contains 0.76 mol N2, 0.18 mol O2, 0.031 mol He and 0.026 mol H2 at 749 mm

Hg. What is the partial pressure of O2?

A) 20 mm Hg

B) 23 mm Hg

C) 140 mm Hg

D) 570 mm Hg

28) What is the total pressure in a 6.00-L flask which contains 0.127 mol of H2(g) and 0.288 mol

of N2(g) at 20.0°C?

A) 0.510 atm

B) 0.681 atm

C) 1.16 atm

D) 1.66 atm

29) What is the mole fraction of in a gas mixture containing 22.3 g of , 15.9 g of , and

whose volume at STP is 80.0L?

A) 0.544

B) 0.456

C) 0.928

D) 0.995

30) The mole fraction of carbon dioxide in a gas mixture is 0.200. There are 0.251 g of nitrogen

and 0.322 g of oxygen in this gas mixture. What is the mass of carbon dioxide in this mixture?

A) 0.216g

B) 0.373g

C) 0.838g

D) 0.0191g

31) 2.13 g of (g) is mixed with 15.0 g of (g) in a 2.35 L container. What is the mole

fraction of (g) present in the mixture?

A) 0.205

B) 0.876

C) 0.118

D) 0.414

32) A 1.000 kg sample of nitroglycerine, C3H5N3O9, explodes and releases gases with a

temperature of 1985°C at 1.100 atm. What is the volume of gas produced?

4 C3H5N3O9(s) → 12 CO2(g) + 10 H2O(g) + 6 N2(g) + O2(g)

A) 742.2 L

B) 3525 L

C) 4730 L

D) 5378 L

33) In the laboratory, hydrogen gas is usually made by the following reaction:

Zn(s) + 2 HCl(aq) → H2(g) + ZnCl2(aq)

How many liters of H2 gas, collected over water at an atmospheric pressure of 752 mm Hg and a

temperature of 21.0°C, can be made from 3.566 g of Zn and excess HCl? The partial pressure of

water vapor is 18.65 mm Hg at 21.0°C.

A) 0.0975 L

B) 1.30 L

C) 1.33 L

D) 1.36 L

34) A 0.600 g sample containing Ag2O and inert material is heated, causing the silver oxide to

decompose according to the following equation:

2 Ag2O(s) → 4 Ag(s) + O2(g)

If 13.8 mL of gas are collected over water at 27°C and 1.00 atm external pressure, what is the

percentage of silver oxide in the sample? The partial pressure of water is 26.7 mm Hg at 27°C.

A) 10.4%

B) 20.9%

C) 41.8%

D) 44.8%

35) What is the average speed (actually the root-mean-square speed) of a neon atom at 27°C?

A) 5.78 m/s

B) 19.3 m/s

C) 183 m/s

D) 609 m/s

36) Which of the following gases has the highest average speed at 400K?

A) N2

B) O2

C) F2

D) Cl2

37) Which of the following gases has the lowest average speed at 25°C?

A) C3H8

B) Kr

C) CH3NH2

D) SO2

38) What is the temperature of NO2 gas if the average speed (actually the root-mean-square

speed) of the molecules is 750 m/s?

A) 1.38 K

B) 1.04 × 103 K

C) 1.38 × 103 K

D) 1.04 × 106 K

39) If NO and NH3 are allowed to effuse through a porous membrane under identical

conditions, the rate of effusion for NH3 will be ________ times that of NO .

A) 0.57

B) 0.75

C) 1.3

D) 1.8

9.3 Short Answer Questions

1) Under the same pressure and temperature conditions, the level of water inside a barometer will

be ________ than the level of mercury inside the barometer by a factor equal to the ratio of the

density of ________ over the density of ________.

2) At an atmospheric pressure of 745 mm Hg, what is the pressure of He gas inside a cylinder

that is attached to an open-end manometer in which the level of mercury in the open side of the

manometer is 25 mm Hg higher than the side that is attached to the gas cylinder?

3) One mole of gas at 25°C in a 1.0-L flask has a ________ pressure than one mole of gas at

25°C in a 5.0-L flask.

4) One mole of gas at 25°C has a ________ volume than one mole of gas at standard

temperature.

5) At STP if 1.00 mole of gas occupies 22.4 L then 0.200 mole of gas would occupy ________ L

under the same conditions.

6) If one mole of gas occupies 22.4 L at STP the same gas would occupy ________ than 22.4 L

at 25°C and 738 mm Hg.

7) If 0.40 mol of NaN3 reacts completely in the reaction shown below, then ________ L of N2

will be produced at STP.

2 NaN3(s) → 2 Na(s) + 3 N2(g)

8) If 1.0 mol of N2 and 3.0 mol of H2 in a closed container initially at STP react completely in

the reaction shown below, then the final pressure in the flask will be ________ atm at 273 K.

N2(g) + 3 H2(g) → 2 NH3(g)

9) In a flask containing 2.00 mol of He, 3.00 mol of Ne, and 5.00 mol of Ar at STP the partial

pressure of He is ________ mm Hg.

10) Gases do not behave ideally under conditions of ________ pressure and ________

temperature.