Worksheet Gas Laws Chapter 12

AP Gases Self-Check Problems (Yes I know the question numbers don’t go in order – live with it.)

1. Approximately how many molecules are in 11 g of carbon dioxide gas? 23 23 23 23 (a) 1.5 x 10 (b) 3 X 10 (c) 6 X 10 (d) 2.4 X 10

2. At STP, 0.20 mole of nitrogen gas, N , has a volume of : 2 (a) 1.12 L (b) 2.24 L (c) 4.48 L (d) 22.4 L

3. A fixed volume of oxygen gas, O , exerts a pressure of 1.00 atm at a temperature 2 o o of 25 C. What is the pressure of the gas when it is heated to 100 C? (a) 0.25 atm (b) 1.25 atm (c) 2.5 atm (d) 4 atm

4. The partial pressures of a gaseous mixture are as follows: hydrogen 200 torr, carbon dioxide 150 torr, methane 320 torr, and ethylene 105 torr. What is the mole percent of hydrogen. (a) 20 (b) 25.8 (c) 38.8 (d) 41.7

5. When the absolute temperature of a fixed quantity of an ideal gas is quadrupled and the pressure is doubled, what is the net effect on the volume of the gas? (a) volume remains constant (b) volume doubles (c) volume quadruples (d) volume increases eight times

6. A mixture of 11 g of CO and 8 g of O and an undetermined amount of H 2 2 2 o occupies 22.4 L at 760 torr and 0 C. How many grams of H are present? 2 (a) 0.1 (b) 0.5 (c) 1 (d) 2

7. The vapor pressure exhibited by a liquid in a closed container depends upon the: (a) shape of the container (b) surface area of the liquid (c) temperature and nature of the liquid (d) amount of liquid present in the container

o 8. What volume of gaseous oxygen, collected at 819 C and 760 torr pressure is formed by the decomposition of 0.2 moles of Ag O? 2Ag O 4 Ag + O 2 2 2 (a) 1.12 L (b) 2.24 L (c) 4.48 L (d) 8.96 L

9. A sample of helium gas, present in a closed container of constant volume, is heated until the absolute temperature has been doubled. Which one of the following properties also doubles? (a) density (b) number of molecules (c) average molecular speed (d) pressure 11. What is the volume of 14 g of nitrogen gas, N , at a pressure of 2 atm and a 2 o temperature of 27 C? (a) 5.6 L (b) 6.15 L (c) 11.2 L (d) 12.3 L

12. At standard temperature and pressure(STP), four balloons are filled each with one gram of different gases: Ar, HCl, N , or NO. Which balloon contains the most 2 molecules of gas? (a) Ar (b) HCl (c) N (d) NO (e) All are the same 2

13. A 0.10 g sample of zinc is added to excess hydrochloric acid. When the reaction is complete, what is the volume of gas, in ml, at STP that was evolved by the metal + 2+ sample? Zn + 2H Zn + H 2 (a) 10 (b) 17 (c) 34 (d) 68

o 14. A weather balloon is filled with 10 L of air at atmospheric conditions, 27 C and 0.982 atm. It is released into the upper atmosphere where the temperature is o 2 C and the pressure is 0.49 atm. What is the new volume of the balloon? -5 (a) 5.8 X 10 L (b) 1.5 L (c) 18 L (d) 20 L (e) 23 L

3 16. The pressure on 525 cm of helium gas is increased from 2 atm to 3 atm at a 3 3 constant temperature. What is the new volume? (a) 263 cm (b) 350 cm 3 3 (c) 788 cm (d) 1575 cm

Use the following choices to select the correct answer for questions 18-21 (a) He (b) Ne (c) Ar (d) Kr (e) all the same

20. With all gases at the same temperature, the one with the largest kinetic energy.

21. With all gases at the same temperature, the one with the highest average velocity.

22. How many liters of H , measured at STP, would be produced from 2.7 g of 2 Al? 2Al + 6HCl 2 AlCl + 3H 3 2 (a) 1.49 L (b) 2.24 L (c) 3.36 L (d) 7.47 L

23. An ideal gas at 300 K and 1 atm is contained in a flexible vessel. Its volume is then reduced to one-half the original volume and the pressure remains unchanged. The new temperature is: (a) 75 K (b) 150 K (c) 300 K (d) 600 K

24. What is the density of argon in a 4.5 L bulb at 0.5 atm and 273 K? (a) 4.5 g/L (b) 8.9 g/L (c) 2.2 g/L (d) 1.8 g/L (e) 0.89 g/L

o 25. If 6.6 g of a gaseous compound occupies a volume of 1.2 L at 27 C and 0.967 atm, the molecular weight of the compound is: (a) 109 (b) 123 (c) 140 (d) 165

26. The kinetic molecular theory of ideal gases assumes that: (a) the collisions of gas molecules are inelastic (b) all gas molecules travel at the same speed (c) gas molecules exert no pressure on the walls (d) the volume of a gas molecule is negligible

27. If a sample of an ideal gas has its pressure doubled and its Kelvin temperature tripled, its volume will be: (a) 3/2 of its original value (b) 1/2 of its original value (c) 2/3 of the original value (d) 6 times the original value

28. Gas A has a volume of 2 L at 250 K and 3 atm. Gas B has a volume of 2 L at 500 K and 6 atm. The ratio: number of molecules of A/ number of molecules B is: (a) 1/1 (b) 2/1 (c) 1/2 (d) 1/4

29. A flask contains 1 g of ethene gas, C H , at STP. It is emptied and the refilled 2 4 with 1.5 g of an unknown gas at STP. What is the molecular weight of the unknown gas? (a) 2.5 (b) 28 (c) 33.6 (d) 42

30. Which gas diffuses the most rapidly? ( All gases are at the same T and P.) (a) Ne (b) O (c) NH (d) SO 2 3 2

31. Gas A has a diffusion rate of 0.0862 cm/s. Under the same experimental conditions, CO has a diffusion rate of 0.1509 cm/s. What is the molecular 2 weight of gas A? (a) 14.4 (b) 25.1 (c) 58.2 (d) 135

32. Calculate the molar mass of an ideal gas which has a density of 1.87 g/L at o 30 C and a pressure of 0.98 atm. (a) 31.2 (b) 39.3 (c) 47.4 (d) 114

33. 16 grams of oxygen, 8 grams of hydrogen, and 32 grams of sulfur dioxide are placed together in a vessel. The total pressure exerted by the mixture of gases if 756 torr. The partial pressure exerted by the oxygen is: (a) 75.6 torr (b) 216 torr (c) 252 torr (d) 756 torr 3 o 34. A 320 cm sample of a mixture of oxygen gas saturated with water vapor at 22 C o exerts a total pressure of 748 torr. At 22 C the vapor pressure of water is 20 torr. Calculate the number of grams of oxygen in the sample. (a) 0.203 (b) 0.405 (c) 0.416 (d) 308

Answers 11. B 25. C 1. A 12. C 26. D 2. C 13. C 27. A 3. B 14. C 28. A 4. B 16. B 29. D 5. B 20. E 30. C 6. C 21. A 31. D 7. C 22. C 32. C 8. D 23. B 33. A 9. D 24. E 34. B