Gases
You must show your work beside each question. Beside each free response problem you need to:
· Write the formula,
· Show the set-up, and
· calculate the answer.
In the Ideal Gas Law: PV = nRT. R = XXXXXXXXXXL•atm/mole•K
Molar volume is XXXXXXXXXXL/mole at STP
1. Sodium bica
onate is reacted with concentrated hydrochloric acid at 37.0 °C and 1.00 atm. The reaction of 6.00 kg of bica
onate with excess hydrochloric acid under these conditions will produce ________ L of CO2. A. 1.09 × 102
B. 2.85 × 104
C. 1.82 × 104
D. 8.70 × 102
E. 1.82 × 103
2. The density of NO2 in a 4.50 L tank at 760.0 to
and 25.0 °C is ________ g/L. A. 1.64
B. 9.30
C. 1.68
D. 1.88
E. 3.27
3. A 255 mL round-bottom flask is weighed and found to have a mass of XXXXXXXXXXg. A few milliliters of an easily vaporized liquid are added to the flask and the flask is immersed in a boiling water bath. All of the liquid vaporizes at the boiling temperature of water, filling the flask with vapor. When all of the liquid has vaporized, the flask is removed from the bath, cooled, dried, and reweighed. The new mass of the flask and the condensed vapor is XXXXXXXXXXg. Which of the following compounds could the liquid be? (Assume the ambient pressure is 1 atm.)
A. C4H10
B. C3H7OH
C. C2H6
D. C2H5OH E. C4H9OH
4. The average kinetic energy of the particles of a gas is directly proportional to ________.
A. the rms speed
B. the square of the rms speed
C. the square root of the rms speed
D. the square of the particle mass
E. the particle mass
5. The kinetic-molecular theory predicts that pressure rises as the temperature of a gas increases because ________.
A. the average kinetic energy of the gas molecules decreases
B. the gas molecules collide more frequently with the wall
C. the gas molecules collide less frequently with the wall
D. the gas molecules collide more energetically with the wall
E. both the gas molecules collide more frequently with the wall and the gas molecules collide more energetically with the wall
6. A
ange the following gases in order of increasing average molecular speed at 25 °C.
Cl2 O2 F2 N2
A. Cl2 < F2 < O2 < N2
B. Cl2 < O2 < F2 < N2
C. N2 < F2 < Cl2 < O2
D. Cl2 < F2 < N2 < O2
E. F2 < O2 < N2 < Cl2
7. A sample of oxygen gas was found to effuse at a rate equal to two times that of an unknown gas. The molecular weight of the unknown gas is ________ g/mol.
A. 64
B. 128
C. 8
D. 16
E. 8.0
8. A mixture of two gases was allowed to effuse from a container. One of the gases escaped from the container 1.43 times as fast as the other one. The two gases could have been ________.
A. CO and SF6 B. O2 and Cl2
C. CO and CO2
D. Cl2 and SF6
E. O2 and SF6
9. A real gas will behave most like an ideal gas under conditions of ________.
A. high temperature and high pressure
B. high temperature and low pressure
C. low temperature and high pressure
D. low temperature and low pressure
E. STP
10. The van der Waals equation for real gases recognizes that ________.
A. gas particles have non-zero volumes and interact with each other
B. molar volumes of gases of different types are different
C. the non-zero volumes of gas particles effectively decrease the amount of "empty space" between them D. the molecular attractions between particles of gas decreases the pressure exerted by the gas E. all of the above statements are true .
11. When gases are treated as real, via use of the van der Waals equation, the actual volume occupied by gas molecules ________ the pressure exerted and the attractive forces between gas molecules ________ the pressure exerted, as compared to an ideal gas.
A. decreases, increases
B. increases, increases
C. increases, decreases
D. does not affect, decreases
E. does not affect, increases
12. If 50.75 g of a gas occupies 10.0 L at STP, 129.3 g of the gas will occupy ________ L at STP. A. 3.92
B. 50.8
C. 12.9
D. 25.5 E. 5.08
13. A sample of a gas originally at 25 °C and 1.00 atm pressure in a 2.5 L container is subject to a pressure of 0.85 atm and a temperature of 15 °C. The final volume of the gas is ________ L.
A. 3.0
B. 2.8
C. 2.6
D. 2.1
E. 0.38
14. The reaction of 50 mL of N2 gas with 150 mL of H2 gas to form ammonia via the equation:
N2 (g) + 3H2 (g) → 2NH3 (g)
will produce ________ mL of ammonia if pressure and temperature are kept constant. A. 250
B. 50
C. 200
D. 150 E. 100
15. The amount of gas that occupies 60.82 L at 31.0 °C and 367 mm Hg is ________ mol. A. 1.18
B. 0.850
C. 894
D. 11.6
E. 0.120
16. A gas in a 325 mL container has a pressure of 695 to
at 19 °C. There are ________ mol of gas in the flask. A. 1.24 × 10-2
B. 1.48 × 10-2
C. 9.42
D. 12.4
E. 80.6
17. The molecular weight of a gas is ________ g/mol if 3.5 g of the gas occupies 2.1 L at STP. A. 41
B. 5.5 × 103
C. 37
D. 4.6 × 102
E. 2.7 × 10-2
18. The volume of hydrogen gas at 38.0 °C and 763 to
that can be produced by the reaction of 4.33 g of zinc with excess sulfuric acid is ________ L.
A. 1.68
B. 2.71 × 10-4
C. 3.69 × 104
D. 2.84
E. 0.592
19. The volume of fluorine gas required to react with 2.67 g of calcium
omide to form calcium fluoride and
omine at 41.0 °C and 4.31 atm is ________ mL.
A. 10.4
B. 210
C. 420
D. 79.9
E. 104
20. Automobile air bags use the decomposition of sodium azide as their source of gas for rapid inflation:
2NaN3 (s) → 2Na (s) + 3N2 (g).
What mass (g) of NaN3 is required to provide 40.0 L of N2 at 25.0 °C and 763 to
? A. 1.64
B. 1.09
C. 160
D. 71.1
E. 107
21. What volume (L) of NH3 gas at STP is produced by the complete reaction of 7.5 g of H2O according to the following reaction?
Mg3N2 (s) + 6H2O (l) → 3Mg(OH)2 (aq) + 2NH3 (g)
A. 3.1
B. 9.3
C. 19
D. 28
E. 0.32
22. The thermal decomposition of potassium chlorate can be used to produce oxygen in the laboratory.
2KClO3 (s) → 2KCl (s) + 3O2 (g)
What volume (L) of O2 gas at 25 °C and 1.00 atm pressure is produced by the decomposition of 7.5 g of KClO3 (s)?
A. 4.5
B. 7.5
C. 2.3
D. 3.7
E. 11
23. A vessel contained N2, Ar, He, and Ne. The total pressure in the vessel was 987 to
. The partial pressures of nitrogen, argon, and helium were 44.0, 486, and 218 to
, respectively. The partial pressure of neon in the vessel was ________ to
.
A. 42.4
B. 521
C. 19.4
D. 239 E. 760
24. A sample of He gas (3.0 L) at 5.6 atm and 25 °C was combined with 4.5 L of Ne gas at 3.6 atm and 25 °C at constant temperature in a 9.0 L flask. The total pressure in the flask was ________ atm. Assume the initial pressure in the flask was 0.00 atm and the temperature upon mixing was 25 °C.
A. 2.6
B. 9.2
C. 1.0
D. 3.7
E. 24
25. In a gas mixture of He, Ne, and Ar with a total pressure of 8.40 atm, the mole fraction of Ar is ________ if the partial pressures of He and Ne are 1.50 and 2.00 atm, respectively.
A. 0.179
B. 0.238
C. 0.357
D XXXXXXXXXXE. 0.417
26. Sodium hydride reacts with excess water to produce aqueous sodium hydroxide and hydrogen gas:
NaH (s) + H2O (l) → NaOH (aq) + H2 (g)
A. sample of NaH weighing ________ g will produce 982 mL of gas at 28.0 °C and 765 to
, when the hydrogen is collected over water. The vapor pressure of water at