PreAP Chemistry Unit 12 Review Sheet
Vocabulary Review: In the space at the left, write the term that correctly completes each statement.
Terms (use each on only once)
Absolute zero, Boyle’s law, Charles’ law, Dalton’s law, diffusion, Graham’s law, Kelvin scale, kinetic theory, pressure, standard temperature
______1. ___ states that the pressure exerted by a gas varies inversely with its volume, if the amount and temperature of the gas remain constant.
______2. A temperature-measuring system in which zero is absolute zero is the ____.
______3. Detecting the odor of a substance released from an open bottle across a room is made possible by ___, the random scattering of gas molecules.
______4. The temperature at which all molecular motion should cease, according to kinetic theory, is called ___.
______5. ___ states that under identical conditions of temperature and pressure, two gases’ relative diffusion rates vary inversely with square roots of their molar masses.
______6. According to the ___, the effects of temperature and pressure on matter can be explained by the motion of its particles.
______7. ___ states that the volume and temperature of a gas vary directly if the amount and pressure of the gas remain constant.
______8. The force per unit areas on a surface is ___.
______9. ___, or 0°C, is one of two standards used to compare volumes of gas.
______10. Adding partial pressures of all the gases in a container to find the total pressure in the container demonstrates _____.
Concept Review:
11. Explain how a gas in a container exerts pressure on the walls of the container.
12. a. How does the pressure of a gas in a closed container change if its molecules strike the walls with greater force.?
b. How does the pressure change if the molecules strike with the same force, but more frequently?
13. How will the pressure of a gas in a closed container change if the volume of the container is reduced by half? Explain why.
14. Samples of two substances, A and B are contact with each other. The mass of a molecules of substance A is twice the mass of a molecules of substance B. The average kinetic energy of the molecules in the two substances is the same.
a. Compare the average velocities of the particles of substances A and B.
b. How do the temperatures of the two substances compare?
15. Describe the spacing of the particles of an ideal gas and the nature of the collisions of these particles.
16. Why does the pressure of a gas increase when the gas is squeezed into a smaller volume?
17. A sample of gas is squeezed until its pressure triples. How is the volume of the gas changed by the squeezing?
18. A sample of gas is heated until its Kelvin temperature doubles. How is the sample’s volume changed by the heating?
Problems:
19. What pressure will be needed to reduce the volume of 77.4 L of helium at 98.0 kPa to a volume of 60.0 L?
20. A 250.0 mL sampe of chlorine gas is collect when the barometric pressure is 105.2 kPa. What is the volume of the sample after the barometer drops to 100.3 kPa?
21. A student collects a 125.0 mL sample of hydrogen. Later, the sample is found to have a volume of 128.6 mL at a temperature of 26°C. At what temperature (in °C) was the hydrogen collected?
22. A balloon has a volume of 10500 L if the temperature is 15°C. If the temperature is -35°C, what will be the volume of the balloon?
23. A gas cylinder has a pressure limit of 25.0 atm. The gas inside the cylinder has a pressure of 5.0 atm 27°C. At what temperature (in °C) will the gas reach the pressure limit of the cylinder?
24. A sample of a gas exerts a pressure of 743 torr when the temperature is 42°C. What will be the pressure when the temperature is decreased to 18°C
25. A sample of ammonia gas occupies a volume of 1.58 L at 22°C and a pressure of 0.983 atm. What volume will the sample occupy at 1.00 atom and 0°C.
26. A student collects 285 mL of oxygen gas at a temperature of 15°C and a pressure of 99.3 kPa. The next day, the same sample occupies 292 mL at a temperature of 11°C. What is the new pressure of the gas?
27. How many moles of acetylene (C2H2) gas occupy a volume of 3.25 L at STP?
28. Determine the volume of 12.3 g of formaldehyde gas (CH2O) at STP?
29. What is the pressure in atmospheres of 10.5 mol of acetylene in a 55.0 L cylinder at 37°C?
30. A sample of carbon monoxide has a volume of 344 mL at 85°C and a pressure of 88.4 kPa. Determine the amount in moles of carbon monoxide present.
31. A 250.0 mL sample of a noble gas collect at 88.1 kPa and 7°C has a mass of 0.378 g. What is the molar mass of the gas? Identify the sample.
32. What volume is occupied by 1.000 g of water vapor at a temperature of 134°C and a pressure of 0.0552 atm?
33. A 5.25 L tank contains 87.0 g of neon gas. At what temperature (in °C) will the tank have a pressure of 19.0 atm?
34. 75.0 mL of chlorine gas were collected over water at a temperature of 26°C when the atmospheric pressure was 751 torr. What volume would the dry gas occupy at 20°C and a pressure of 763 torr?
35. A piece of aluminum with a mass of 4.25 g is reacted with hydrochloric acid to generate hydrogen gass. The hydrogen is collected at a temperature of 15°C and a pressure of 94.4 kPa. What volume of hydrogen is produced?
36. Carbon disulfide burns in air to produce carbon dioxide and sulfur dioxide gas. Determine the mass of carbon disulfide required to produce 15.7 L of sulfur dioxide at 25°C and 99.4 kPa.
37. Compare the rate of effusion of neon to the rate of effusion of helium.
38. A sample of oxygen took 55 seconds to travel a certain distance. How long would it take for the same number of moles of nitrogen to travel the same distance.
39. A sample of hydrogen gas traveled 45 m in a given amount of time. An unknown gas traveled 7.6 m in the same amount of time. What is the formula mass of the unknown gas?
Answers:
1. Boyles’ law 6. kinetic theory
2. Kelvin scale 7. Charles’ law
3. diffusion 8. Pressure
4. absolute zero 9. standard temperature
5. Graham’s law 10. Dalton’s law
11. The molecules are constantly colliding with the walls and exerting force on them
12. a. The pressure increases.
b. The pressure increases.
13. The pressure will increase. The molecules are confined to a smaller space and will strike the walls of the container more frequently creating more pressure.
14. a. The average velocity of the particles of B is √2 times the velocity of the particles of A.
b. It is the same because the average kinetic energy of their molecules is the same.
15. The spacing is much greater than the size of the particles. No kinetic energy is lost in the collisions.
16. Squeezing concentrates the gas particles in a smaller space. As a result, they collide with each other and the walls of their container more often.
17. The volume is reduced to one-third the original volume
18. The volume doubles.
19. 126 kPa 25. 1.44 L 31. 40.0 g/mol; Ag
20. 262.2 mL 26. 95.6 kPa 32. 33.6 L
21. 18°C 27. 0.145 mol 33. 9°C
22. 8680 L 28. 9.17 L 34. 69.9 mL
23. 1227 °C 29. 4.86 atm 35. 5.99 L
24. 686 torr 30. 0.0102 mol 36. 24.0 g
37. RateNe = 0.447RateHe 38. 51 seconds 39. 71 g/mol