The Gas Laws:

  A temperature and pressure are needed to describe any volume of gas.

The volume of a gas means nothing unless the conditions under which it was collected are known.

Temperature - Temperature changes cause particle motion changes which cause a volume change.Pressure - Gases can be compressed, or squeezed, causing a change in the gas volume.

Standard temperature and pressure - STP:

Standard temperature is 0 oCelsius.

All gas calculations must use Kelvin temperatures.

K = Co + 273

Notice it is K - not oK

You say "Kelvins" - not "Degrees Kelvin"

Standard pressure is 1 atmosphere (at sea-level).

1 atm = 760 mm Hg = 101 kPa = 101,300 Pascals = 1013 mb = 29.92 in Hg

mm Hg is millimeters of mercury. This describes the height of a vertical column of mercury that the pressure will support against gravity. The unit Torr can be used to indicate mm Hg. The barometric pressure reported in U.S. weather reports is usually expressed as inches of mercury. There are 25.4 millimeters in one inch.

kPa is kiloPascals. A Pascal is a unit of force equal to one Newton / m2. It is describing the pressure exerted by the molecules of the gas striking a surface.

mb is millibars. One millibar is equal to 100 Newtons / m2.

When working with gas laws, all pressure units must be the same in any calculation.If needed, be able to convert from one pressure unit to another.

To be successful working gas law problems, do the following:

Read the question to see what conditions change.Decide which gas law to use and write its equation.Reread the question to see what question is asked.Manipulate the gas law equation if needed.Plug numbers and units into the equation.Pickup your calculator and punch buttons.ok Write the answer to the problem and circle it.

Boyle's Law: used when the pressure of a gas changes.

At constant temperature, pressure exerted by a gas varies inversely with its volume.

If the volume of a container decreases, pressure of the gas increases.

If the volume of a container increases, pressure of the gas decreases.

Boyle's Law is expressed by the equation:

Concept Understanding:

1. Do the following conversions:

a. 27 K to Celcius

b. 1450 oC to K

c. 1.25 atmospheres to inches of Hg

d. 500. millimeters of Hg to kPa

e. Convert your answer in d to millibars.

2. Work the following Boyle's Law practice problems:

a. 10.0 dm3 of a gas are collected at STP. What will be the volume if the pressure changes to 9.5 kPa while the temperature remains unchanged?

b. What is the volume occupied by 5.0 dm3 of a gas at STP if the pressure increases to 500. kPa and the temperature remains constant?

c. 90.5 cm3 of a gas are collected at 97.5 kilopascals. If the temperature does not change, at what pressure will the volume be 70.0 cm3?

Charles' Law: used when the temperature of a gas changes.

At constant pressure, volume of a gas varies directly with the Kelvin temperature.

As the temperature of a gas increases, the volume of the gas increases.

As the temperature of a gas decreases, the volume of the gas decreases.

Charles' Law is expressed by the equation:

Concept Understanding:

1.Work the following Charles' Law practice problems:

a.) A gas has a volume of 495 cm3 at STP. Assuming no pressure change, what volume will the gas occupy if the temperature is doubled?

b.) A sample of hydrogen gas occupies 2.5 dm3 at 20.0 oC. What will be its volume at -10.0 oC?

c.) A gas occupies a volume of 500. cm3 at 120 oC. Assume the pressure does not change, to what temperature must the gas be cooled for the volume to drop 10.0%?

The Combined Gas Law: used when both pressure and temperature change.

A combination of Boyle's Law and Charles' Law.

The Combined Gas Law is expressed by the equation:

Concept Understanding:

1. Work the following Combined Gas Law practice problems:

a. Calculate the volume of a gas at STP if 5.05 dm3 of the gas are collected at 27.5 oC and 95.0 kPa.

b. A gas occupied 355 cm3 at a pressure of 99.5 kPa and a temperature of 22.0 oC. The pressure increases 100. kPa and the temperature drops 7.0 Co. What is the new volume?

c. Assume the respiratory rate for a person is 15 breaths per minute and one breath contains 500. cm3

of air at 20.0 oC and 99.5 kPa. What volume of air, in cubic meters, corrected to standard conditions, does an individual breathe in one day?

Dalton's Law of Partial Pressure: used with a mixture of gases.

The total pressure in a container is the sum of the partial pressures of all the gases in the container.

When a gas is collected by water displacement in the lab, the collected sample will contain water vapor. A calculation using Dalton's Law must be used to determine the pressure of the dry gas (the gas with no water vapor). To do this calculation, you will need the vapor pressure of water at the collected temperature.

Concept Understanding:

1. Work the following Dalton' Law practice problems:

a.The total pressure in a closed container of three mixed gases is 96.4 kPa. The partial pressure of hydrogen in the mixture is 13.5 kPa and the partial pressure of oxygen is 29.3 kPa. The third gas in the mixture is methane, what is its partial pressure?

b. 100. cm3 of hydrogen gas are collected using water displacement in the lab. The conditions at the time are 98.5 kPa and 24 oC. What volume of dry hydrogen is collected? P2 is 98.5 kPa

c.325 cm3 of oxygen are collected over water at 10 oC and 98 kPa. What will be the volume of the dry gas at 101 kPa and 10 oC?

USING CHARLES’S LAW TO DETERMINE ABSOLUTE ZEROhttp://faculty.rpcs.org/millerd/Chemistry%20R/Labs/Charles%20Law%20Lab.htm Have you noticed that the tires on an automobile appear to be a little flat on a cold winter’s day? Conversely, a balloon inflated in a cold room will expand when taken into a warm room. These observations suggest that there is a relationship between the temperature and volume of a gas.

The volume-temperature relationship is quantified in Charles’s Law. The law states that as the temperature of a gas decreases, the volume of the gas decreases proportionally. An ideal gas, for example, would decrease in volume by 1/273 of its original volume for each Celsius degree the temperature decreases. If the temperature decreased sufficiently, the volume should decrease to zero. Real gases, however, liquefy and solidify long before this theoretical limit, called absolute zero, is reached. By using air as a sample of a real gas and limiting the temperature range, it is possible to estimate the temperature that would correspond to absolute zero.

In this experiment, you will measure the volume of a sample of air at a variety of temperatures and analyze the data to determine the relationship between the temperature and the volume of a gas. You will also extrapolate from your experiment data to determine absolute zero – the temperature at which gas theoretically has no volume.

Pre-Lab Questions:On a clean sheet of paper set-up for your lab (Title, page headings)

1. Restate the purpose of the lab in your own words, and write out Charles’ Law in mathematical form. 2. Write a hypothesis. Remember to include both a prediction and justification. You should predict the relationship and

absolute zero.3. Identify variables (independent, dependent and constant variables)4. Procedures: After reading through the procedures, write a brief explanation, with diagrams explaining what you are going

to do in less detail. You should address the following:a. Why you are using different temperature water bathsb. When and why you hold the end of the pipet closed. (explain step 7)c. How you will calculate the total volume of the gas at each temperature. (explain step 8)

5. Data: Set up data table to collect all necessary data a. Total drops of water in pipette at room temperature (3 trials)b. Room temperature in Celsius and in Kelvinc. Total drops of water in pipette for each trial for each temperatured. Total volume for each temperature (add a + c)

Purpose: Demonstrate the relationship between the temperature of a gas and its volume. Graph the relationship between volume and Celsius temperature and between volume and Kelvin temperature. Estimate the temperature of absolute zero by extrapolation.

Materials:Goggles Thermometer

Hot plate 2 400 mL beakers

Thin stem pipette Timer or stopwatch

Paper towel

Procedure: Job 1: Calibrating the Pipette

1. Obtain a pipette. 2. Pull the end off to make it smaller (this will be demonstrated)3. Name and label your pipette w/ permanent marker4. Completely fill the pipette with water (see hint 1 below)5. Expel the water one drop at a time and count the drops. (see hint 2 below)6. You need to do this at least two times to see if you get the same results.

Hint 1: To make sure the pipette is filled, first draw in as much water as possible by squeezing the bulb. Then, holding the pipette by the bulb with the stem pointing upward, slowly squeeze the bulb to eject any air left in the bulb. Keep this pressure on the bulb, bend the stem of the bulb and place the tip of the step into the breaker of room temperature water. Release the pressure on the bulb, and the pipette will fill completely. Repeat this procedure, if necessary, until no air remains in the bulb or step of the pipette.

Hint 2 : You may want to drop the droplets in a line along the desk in case you lose count. There will be around 200-300 drops

Job 2: Set up hot water baths 1. Fill two 400 mL beakers half to 2/3 full with tap water. 2. Determine room temperature and record it in your data table. 3. Begin heating the water in one beaker to a temperature that is 5 °C above room temperature.

Job 3: Set up graphs1. Using Excel or Graphical Analysis in the science folder, set up the data tables for each graph (proper labels, units, titles,

scales) 2. You will be plotting the relative volume (in drops) versus temperature (in Kelvin). 3. You will also be plotting a second graph using the same data, but using degrees Celsius as the unit of temperature. Begin

the volume scale at 0 drops, but start the temperature scale at –300 °C.

Job 4: Taking Data4. Holding the empty pipette by the stem, immerse the bulb in the warm water for 2 minutes so that the air in the pipette

reaches the temperature of the water. Do not submerge the whole pipet, some of the stem should stick out of the water. Make sure the temperature remains 5°C above room temperature. This may involve removing the beaker from the hot plate or adding cool water.

5. Before removing from the warm water, pinch the stem of the pipette to seal off the bulb by bending the stem downward. Make sure you keep the pipette sealed.

6. Place the bulb in the other beaker of water, which is at room temperature. 7. Still pinching the stem, immerse the entire pipette, including the stem in the water. Release the stem underwater. A small

amount of water should be drawn up into the pipette. This water is equal in volume to the amount of gas lost when the pipette bulb was heated and the air inside it expanded.

8. Remover the pipette from the beaker. Dry the outside of the pipette with a paper towel. 9. Expel the water, counting the number of drops of water that were drawn into the pipette. 10. Add this number of drops to the initial volume (the number of drops you counted in step 5) and record this volume in

your data table. 11. Repeat this procedure at a temperature that is 5 °C above the previous trial until the water temperature is about 40 °C.

Record your temperature and the corresponding volume for each trial.

Analyzing Data: 1. (5 pts) Plot a graph of the relative volume (in drops) versus temperature (in Kelvin). Remember, the independent variable

always goes on the x-axis.2. (1 pt) Draw a best-fit straight line through the data points. 3. (5 pts) Plot a second graph using the same data, but using degrees Celsius as the unit of temperature. Begin the volume

scale at 0 drops, but start the temperature scale at –300 °C. 4. (1 pt) Again, draw a best-fit straight line through the data points. 5. (1 pt) Write the equation for your line of best fit (Celsius graph). 6. (2 pts) Calculate the temperature at which volume is zero. 7. (2 pts) If not already done for you by the computer, use dashes to extend the straight line from the lowest data point to the

horizontal axis. According to your graph, what is the Celsius temperature at which the volume would be equal to 0? 8. (3 pts) Calculate a percent error for your estimate of absolute zero.

Conclusion and Error Analysis:1. (1 pt) Summarize the purpose of this experiment.2. (2 pts) Does your data support your hypothesis? (Does it show the expected relationship and correct value for absolute

zero?) Refer to data to defend your claim. 3. (5 pts) Interpret the results of this lab in terms of the kinetic molecular theory of gases.4. (1 pt) If you percent error is less than 15% you can say that your results are valid. Are your results valid? 5. (4 pts) What are the two most significant errors that contributed to your results? Please explain why they were errors –

don’t just list them. 6. (2 pts) The pressure did not vary during the experiment, because all the trials were performed at constant room

(atmospheric) pressure. If the pressure had varied, how would it have affected your results? EXPLAIN.

Gas Laws Name: ___________________________ Page 7 of 17

Graphs must Be scatter plots (NO BAR GRAPHS or line

graphs) Have x and y-axis labeled with correct units. Have temperature on the x axis. Have a title Have a line of best fit

Grading: Title and formatting (5 pts)Purpose (5 pts)Hypothesis (10 pts)Variables (5 pts)Procedures (10 pts)Data (15 pts)Analysis (20 pts)Conclusion (15 pts)

Total Volume = (0.8639 drop/oC) T + 196.11 drops

Gas Laws Name: ___________________________ Page 8 of 17

Graph Instruction for Excel1. Open Excel2. In A1 type your name. In Student does not turn in homework. In C1 type your lab partner’s name. 3. In A2 put your title4. In A3 type “Purpose: then your purpose.”5. In A4 Type “Data:”6. In A5 Type “Temperature (T2)” In B5 type the value of your cold temperature.7. In A6 Type “Total Drops (V1)” In B6 type the value of your total drops.8. In A7 Type “Temperature (degrees C)”9. In B7 type “Δ Volume”10. In B8 - type your measure # of drops change for each temperature. (This comes from your raw data)11. In C7 type “Total volume after heating.”12. In C8 – Type “=” put in the value from B6 “+” then click on cell B8.

13. Press enter then arrow back to cell B8. Move your cursor over the small square at the

bottom right of B8. When the cursor changes to the small + you see here.

14. Highlight B8 - ??(measured values) and C8-?? Then click this button 15. Choose XY scatter.16. Complete the graph with a title, label the X and Y axis. And finish17. Click on the Series box and press delete.

18. With the graph selected, click Chart/Add Trendline 19. The default is linear. Click the Options tab Check Display equation on Chart. Click OK

20. When the equation shows Copy “Total Volume” from C7 then move your cursor beside the “y” delete the letter “y” and paste. Then type “T” in Place of “x”. Type the units for the slope as seen below. Highlight all the text in the box and change the size of the font to 12 point. Your final formula should look like this

21. In A? (a cell below your graph) type “Conclusion:” in the next A cell type your conclusion. Make sure that the graph is NOT selected.

You can change font size, bold, center text and more to make the print out pretty.

Note: The title should be Y vs. X

Gas Laws Name: ___________________________ Page 9 of 17

Molecular Mass Determination of Butane (C4H10)Purpose: To determine the molar mass of butane (C4H10)

Equipment: Erlenmeyer Flask Water basinPiece of glass Butane lighter Graduated cylinder

Procedure:1. Make sure the butane lighter is dry, and find its mass.2. Fill the water basin with water.3. Completely fill the flask with water.4. Turn the flask upside down in the water basin, making sure there are no air

bubbles are inside.5. Bubble the gas into the flask, until only 2 or 3 cm of water remains.6. Put the piece of glass over the top of the flask and turn it over.7. Using the graduated cylinder, measure the amount of water needed to

completely refill the flask. This is how much gas was collected.8. Completely dry the lighter and find its mass.9. Clean and dry the equipment and lab station.10. Find the room temperature and barometric pressure.11. Write a lab report: data table, calculations (molar mass and % error), conclusion.

Use your own paper. Ignore the questions although they may help you figure out want to do with the calculations portion of your lab report.

Questions and calculations: (Show your work and include units.)1. How much butane did it take to fill the flask (mass)?

2. What was the volume of the gas in mL?

3. How many liters of gas is this?

4. How many moles of gas is this?

5. What is the density of the butane in g/L

6. What is the molar mass of butane? (Use this formula – )

7. The formula for butane is C4H10. What is the mass of 1.00 mole of C4H10?

Gas Laws Name: ___________________________ Page 10 of 17

Gas Law ProblemsAbbreviations Conversionsatm - atmosphere K = °C + 273mmHg - millimeters of mercury 1 cm3 (cubic centimeter) = 1 mL (milliliter)torr - another name for mmHg 1 dm3 (cubic decimeter) = 1 L (liter) = 1000 mLPa - Pascal (kPa = kilo Pascal) Standard ConditionsK - Kelvin 0.00 °C = 273 K °C - degrees Celsius 1.00 atm = 760.0 mmHg = 101.325 kPa = 101,325 Pa

Boyle’s Law

1. A gas occupies 12.3 liters at a pressure of 40.0 mmHg. What is the volume when the pressure is increased to 60.0 mmHg?

2. If a gas at 25.0 °C occupies 3.60 liters at a pressure of 1.00 atm, what will be its volume at a pressure of 2.50 atm?

3. To what pressure must a gas be compressed in order to get into a 3.00 cubic foot tank the entire weight of a gas that occupies 400.0 cu. ft. at standard pressure?

4. A gas occupies 1.56 L at 1.00 atm. What will be the volume of this gas if the pressure becomes 3.00 atm?

5. A gas occupies 11.2 liters at 0.860 atm. What is the pressure if the volume becomes 15.0 L?

6. 500.0 mL of a gas is collected at 745.0 mmHg. What will the volume be at standard pressure?

7. Convert 338 L at 63.0 atm to its new volume at standard pressure.

8. Convert 273.15 mL at 166.0 mm of Hg to its new volume at standard pressure.

9. Convert 77.0 L at 18.0 mm of Hg to its new volume at standard pressure.

10. When the pressure on a gas increases, will the volume increase or decrease?

11. If the pressure on a gas is decreased by one-half, how large will the volume change be?

12. A gas occupies 4.31 liters at a pressure of 0.755 atm. Determine the volume if the pressure is increased to 1.25 atm.

13. A gas occupies 25.3 mL at a pressure of 790.5 mmHg. Determine the volume if the pressure is reduced to 0.804 atm.

14. A container of oxygen has a volume of 30.0 mL and a pressure of 4.00 atm. If the pressure of the oxygen gas is reduced to 2.00 atm and the temperature is kept constant, what is the new volume of the oxygen gas?

15. A tank of nitrogen has a volume of 14.0 L and a pressure of 760.0 mmHg. Find the volume of the nitrogen when its pressure is changed to 400.0 mmHg while the temperature is held constant.

16. A 40.0 L tank of ammonia has a pressure of 8.00 atm. Calculate the volume of the ammonia if its pressure is changed to 12.0 atm while its temperature remains constant.

17. Two hundred liters of helium at 2.00 atm and 28.0 °C is placed into a tank with an internal pressure of 600.0 kPa. Find the volume of the helium after it is compressed into the tank when the temperature of the tank remains 28.0 °C.

18. You are now wearing scuba gear and swimming under water at a depth of 66.0 ft. You are breathing air at 3.00 atm and your lung volume is 10.0 L. Your scuba gauge indicate that your air supply is low so, to conserve air, you make a terrible and fatal mistake: you hold your breath while you surface. What happens to your lungs?

Answers on page 14.

Gas Laws Name: ___________________________ Page 11 of 1719. A 1.5 liter flask is filled with nitrogen at a pressure of 12 atmospheres. What size flask would be

required to hold this gas at a pressure of 2.0 atmospheres?

20. 300 mL of O2 are collected at a pressure of 645 mm of mercury. What volume will this gas have at one atmosphere pressure?

21. How many cubic feet of air at standard conditions (1.00 atm.) are required to inflate a bicycle tire of 0.50 cu. ft. to a pressure of 3.00 atmospheres?

22. How much will the volume of 75.0 mL of neon change if the pressure is lowered from 50.0 torr to 8.00 torr?

23. A tank of helium has a volume of 50.0 liters and is under a pressure of 2000.0 p.s.i.. This gas is allowed to flow into a blimp until the pressure in the tank drops to 40.00 p.s.i. and the pressure in the blimp is 30.00 p.s.i.. What will be the volume of the blimp?

24. What pressure is required to compress 196.0 liters of air at 1.00 atmosphere into a cylinder whose volume is 26.0 liters?

Charles’ Law

25. Calculate the decrease in temperature when 2.00 L at 20.0 °C is compressed to 1.00 L.

26. 600.0 mL of air is at 20.0 °C. What is the volume at 60.0 °C?

27. A gas occupies 900.0 mL at a temperature of 27.0 °C. What is the volume at 132.0 °C?

28. What change in volume results if 60.0 mL of gas is cooled from 33.0 °C to 5.00 °C?

29. Given 300.0 mL of a gas at 17.0 °C. What is its volume at 10.0 °C?

30. At 27.00 °C a gas has a volume of 6.00 L. What will the volume be at 150.0 °C?

31. At 210.0 °C a gas has a volume of 8.00 L. What is the volume of this gas at –23.0 °C?

32. The temperature of a 4.00 L sample of gas is changed from 10.0 °C to 20.0 °C. What will the volume of this gas be at the new temperature if the pressure is held constant?

33. Carbon dioxide is usually formed when gasoline is burned. If 30.0 L of CO2 is produced at a temperature of 1.00 x103 °C and allowed to reach room temperature (25.0 °C) without any pressure changes, what is the new volume of the carbon dioxide?

34. A 600.0 mL sample of nitrogen is warmed from 77.0 °C to 86.0 °C. Find its new volume if the pressure remains constant.

35. What volume change occurs to a 400.0 mL gas sample as the temperature increases from 22.0 °C to 30.0 °C?

36. A gas syringe contains 56.05 milliliters of a gas at 315.1 K. Determine the volume that the gas will occupy if the temperature is increased to 380.5 K

37. A gas syringe contains 42.3 milliliters of a gas at 98.15 °C. Determine the volume that the gas will occupy if the temperature is decreased to -18.50 °C.

38. When the temperature of a gas decreases, does the volume increase or decrease?

39. If the Kelvin temperature of a gas is doubled, the volume of the gas will increase by ____.

40. If 540.0 mL of nitrogen at 0.00 °C is heated to a temperature of 100.0 °C what will be the new volume of the gas?

41. A balloon has a volume of 2500.0 mL on a day when the temperature is 30.0 °C. If the temperature at night falls to 10.0 °C, what will be the volume of the balloon if the pressure remains constant?

Gas Laws Name: ___________________________ Page 12 of 1742. When 50.0 liters of oxygen at 20.0 °C is compressed to 5.00 liters, what is the new temperature?

43. If 15.0 liters of neon at 25.0 °C is allowed to expand to 45.0 liters, what is the new temperature?

44. 3.50 liters of a gas at 727.0 °C will occupy how many liters at 153.0 °C?

45. Determine the pressure change when a constant volume of gas at 1.00 atm is heated from 20.0 °C to 30.0 °C.

46. A gas has a pressure of 0.370 atm at 50.0 °C. What is the pressure at standard temperature?

47. A gas has a pressure of 699.0 mmHg at 40.0 °C. What is the temperature at standard pressure?

48. If a gas is cooled from 323.0 K to 273.15 K and the volume is kept constant what final pressure would result if the original pressure was 750.0 mmHg?

49. If a gas in a closed container is pressurized from 15.0 atmospheres to 16.0 atmospheres and its original temperature was 25.0 °C, what would the final temperature of the gas be?

50. A 30.0 L sample of nitrogen inside a metal container at 20.0 °C is placed inside an oven whose temperature is 50.0 °C. The pressure inside the container at 20.0 °C was at 3.00 atm. What is the pressure of the nitrogen after its temperature is increased?

51. A sample of gas at 3.00 x 103 mmHg inside a steel tank is cooled from 500.0 °C to 0.00 °C. What is the final pressure of the gas in the steel tank?

52. The temperature of a sample of gas in a steel container at 30.0 kPa is increased from -100.0 °C to 1.00 x 103 °C. What is the final pressure inside the tank?

53. Calculate the final pressure inside a scuba tank after it cools from 1.00 x 103 °C to 25.0 °C. The initial pressure in the tank is 130.0 atm.

Dalton’s Law

54. A container holds three gases: oxygen, carbon dioxide, and helium. The partial pressures of the three gases are 2.00 atm, 3.00 atm, and 4.00 atm, respectively. What is the total pressure inside the container?

55. A container with two gases, helium and argon, is 30.0% by volume helium. Calculate the partial pressure of helium and argon if the total pressure inside the container is 4.00 atm.

56. If 60.0 L of nitrogen is collected over water at 40.0 °C when the atmospheric pressure is 760.0 mmHg, what is the partial pressure of the nitrogen?

57. 80.0 liters of oxygen is collected over water at 50.0 °C. The atmospheric pressure in the room is 96.00 kPa. What is the partial pressure of the oxygen?

58. A tank contains 480.0 grams of oxygen and 80.00 grams of helium at a total pressure of 7.00 atmospheres. Calculate the following.

How many moles of O2 are in the tank?

How many moles of He are in the tank?

Partial pressure of O2.

Total moles of gas in tank.

Partial pressure of He.

59. A mixture of 14.0 grams of hydrogen, 84.0 grams of nitrogen, and 2.0 moles of oxygen are placed in a flask. When the partial pressure of the oxygen is 78.00 mm of mercury, what is the total pressure in the flask?

Gas Laws Name: ___________________________ Page 13 of 1760. A flask contains 2.00 moles of nitrogen and 2.00 moles of helium. How many grams of argon must be

pumped into the flask in order to make the partial pressure of argon twice that of helium?

Combined Gas Law

61. A gas has a volume of 800.0 mL at –23.00 °C and 300.0 torr. What would the volume of the gas be at 227.0 °C and 600.0 torr of pressure?

62. 500.0 liters of a gas are prepared at 700.0 mmHg and 200.0 °C. The gas is placed into a tank under high pressure. When the tank cools to 20.0 °C, the pressure of the gas is 30.0 atm. What is the volume of the gas?

63. What is the final volume of a 400.0 mL gas sample that is subjected to a temperature change from 22.0 °C to 30.0 °C and a pressure change from 760.0 mmHg to 360.0 mmHg?

64. What is the volume of gas at 2.00 atm and 200.0 K if its original volume was 300.0 L at 0.250 atm and 400.0 K.

65. At conditions of 785.0 torr of pressure and 15.0 °C temperature, a gas occupies a volume of 45.5 mL. What will be the volume of the same gas at 745.0 torr and 30.0 °C?

66. A gas occupies a volume of 34.2 mL at a temperature of 15.0 °C and a pressure of 800.0 torr. What will be the volume of this gas at standard conditions?

67. The volume of a gas originally at standard temperature and pressure was recorded as 488.8 mL. What volume would the same gas occupy when subjected to a pressure of 100.0 atm and temperature of -245.0 °C?

68. At a pressure of 780.0 mmHg and 24.2 °C, a certain gas has a volume of 350.0 mL. What will be the volume of this gas under STP

69. A gas sample occupies 3.25 liters at 24.5 °C and 1825 mmHg. Determine the temperature at which the gas will occupy 4250 mL at 1.50 atm.

70. What is the volume at STP of 720.0 mL of a gas collected at 20.0 °C and 3.00 atm pressure?

71. 2.00 liters of hydrogen, originally at 25.0 °C and 750.0 mm of mercury, are heated until a volume of 20.0 liters and a pressure of 3.50 atmospheres is reached. What is the new temperature?

72. A gas balloon has a volume of 106.0 liters when the temperature is 45.0 °C and the pressure is 740.0 mm of mercury. What will its volume be at 20.0 °C and 780 .0 mm of mercury pressure?

73. If the absolute temperature of a given quantity of gas is doubled and the pressure tripled, what happens to the volume of the gas?

74. 73.0 mL of nitrogen at STP is heated to 80.0 °C and the volume increase to 4.53 L. What is the new pressure?

75. 500.0 mL of a gas was collected at 20.0 °C and 720.0 mmHg. What is its volume at STP?

76. A sample of gas occupies 50.0 L at 15.0 °C and 640.0 mmHg pressure. What is the volume at STP?

77. A gas is heated from 263.0 K to 298.0 K and the volume is increased from 24.0 liters to 35.0 liters by moving a large piston within a cylinder. If the original pressure was 1.00 atm, what would the final pressure be?

78. The pressure of a gas is reduced from 1200.0 mmHg to 850.0 mmHg as the volume of its container is increased by moving a piston from 85.0 mL to 350.0 mL. What would the final temperature be if the original temperature was 90.0 °C?

Gas Laws Name: ___________________________ Page 14 of 1779. If a gas is heated from 298.0 K to 398.0 K and the pressure is increased from 2.230 x 103 mmHg to 4.560

x 103 mmHg what final volume would result if the volume is allowed to change from an initial volume of 60.0 liters?

Combined Gas Law (requires Dalton’s Law also)

IMPORTANT NOTE: A gas collected over water is always considered to be saturated with water vapor. The vapor pressure of water varies with temperature and must be looked up in a reference source.

80. 690.0 mL of oxygen are collected over water at 26.0 °C (v.p. of H2O = 25.2 mm) and a total pressure of 725.0 mm of mercury. What is the volume of dry oxygen at 52.0 °C and 800.0 mm pressure?

81. 400.0 mL of hydrogen are collected over water at 18.0 °C and a total pressure of 740.0 mm of mercury. (v.p. of H2O at 18° = 15.5 mm) What is the partial pressure of H2? c) What is the volume of DRY hydrogen at STP? What is the partial pressure of H2O?

82. 45.0 mL of wet argon gas is collected at 729.3 mmHg and 25.0 °C. What would be the volume of this dry gas at standard conditions?

83. 19.1 L of He gas is collected over water at 681.3 mmHg and 18.5 °C. What would be the volume of this dry gas at standard conditions?

84. 6.12 L of wet xenon gas is collected at 2.00 x 102 kPa and 80.0 °C. What would be the volume of this dry gas at standard conditions?

85. A sample of oxygen collected over water when the atmospheric pressure was 1.002 atm and the room temperature, 25.5 °C occupied 105.8 mL. What would be the volume of this dry gas at standard conditions?

86. 1.000 L of hydrogen gas is collected over water at 30.0 °C at a pressure of 831.8 mmHg. Find the volume of dry hydrogen collected at STP.

87. 50.6 mL of a gas is collected over water at 18.0 °C and 755.5 mmHg pressure. What is the volume of dry gas at STP?

Ideal Gas Law (some also using Dalton’s Law)

88. How many moles of gas are contained in 890.0 mL at 21.0 °C and 750.0 mmHg pressure?

89. 1.09 g of H2 is contained in a 2.00 L container at 20.0 °C. What is the pressure in this container in mmHg?

90. Calculate the volume 3.00 moles of a gas will occupy at 24.0 °C and 762.4 mmHg.

91. What volume will 20.0 g of Argon occupy at STP?

92. How many moles of gas would be present in a gas trapped within a 100.0 mL vessel at 25.0 °C at a pressure of 2.50 atmospheres?

93. How many moles of a gas would be present in a gas trapped within a 37.0 liter vessel at 80.00 °C at a pressure of 2.50 atm?

94. If the number of moles of a gas are doubled at the same temperature and pressure, will the volume increase or decrease?

95. What volume will 1.27 moles of helium gas occupy at STP?

96. At what pressure would 0.150 mole of nitrogen gas at 23.0 °C occupy 8.90 L?

97. What volume would 32.0 g of NO2 gas occupy at 3.12 atm and 18.0 °C?

98. Find the volume of 2.40 mol of gas whose temperature is 50.0 °C and whose pressure is 2.00 atm.

Gas Laws Name: ___________________________ Page 15 of 1799. Calculate the molecular weight of a gas if 35.44 g of the gas stored in a 7.50 L tank exerts a pressure of

60.0 atm at a constant temperature of 35.5 °C

100. How many moles of gas are contained in a 50.0 L cylinder at a pressure of 100.0 atm and a temperature of 35.0 °C?

101. Determine the number of moles of Krypton contained in a 3.25 liter gas tank at 5.80 atm and 25.5 °C. If the gas is Oxygen instead of Krypton, will the answer be the same? Why or Why not?

102. Determine the number of grams of carbon dioxide in a 450.6 milliliter tank at 1.80 atm and -50.5 °C.

103. Determine the volume of occupied by 2.34 grams of carbon dioxide gas at STP.

104. A sample of argon gas at STP occupies 56.2 liters. Determine the number of moles of argon and the mass in the sample.

105. At what temperature will 0.654 moles of neon gas occupy 12.30 liters at 1.95 atmospheres?

106. A 40.0 g gas sample occupies 11.2 L at STP. Find the molecular weight of this gas.

107. 20.83 g. of a gas occupies 4.167 L at 79.97 kPa at 30.0 °C. What is its molecular weight?

108. At STP 150.0 mL of an unknown gas has a mass of 0.250 gram. Calculate its molar mass.

109. 1.089 g of a gas occupies 4.50 L at 20.5 °C and 0.890 atm. What is its molar mass?

110. 0.190 g of a gas occupies 250.0 mL at STP. What is its molar mass? What gas is it? Hint - calculate molar mass of the gas.

111. If 9.006 grams of a gas are enclosed in a 50.00 liter vessel at 273.15 K and 2.000 atmospheres of pressure, what is the molar mass of the gas? What gas is this?

112. What pressure in atmospheres will 1.36 kg of N2O gas exert when it is compressed in a 25.0 L cylinder and is stored in an outdoor shed where the temperature can reach 59°C during the summer?

113. Aluminum chloride sublimes at high temperatures. What density will the vapor have at 225°C and 0.939 atm pressure?

114. An unknown gas has a density of 0.0262 g/mL at a pressure of 0.918 atm and a temperature of 10.°C. What is the molar mass of the gas?

115. A large balloon contains 11.7 g of helium. What volume will the helium occupy at an altitude of 10 000 m, where the atmospheric pressure is 0.262 atm and the temperature is -50.°C?

116. A student collects ethane by water displacement at a temperature of 15°C (vapor pressure of water is 1.5988 kPa) and a total pressure of 100.0 kPa. The volume of the collection bottle is 245 mL. How many moles of ethane are in the bottle?

117. A reaction yields 3.75 L of nitrogen monoxide. The volume is measured at 19°C and at a pressure of 1.10 atm. What mass of NO was produced by the reaction?

118. A reaction has a theoretical yield of 8.83 g of ammonia. The reaction gives off 10.24 L of ammonia measured at 52°C and 105.3 kPa. What was the percent yield of the reaction?

119. An unknown gas has a density of 0.405 g/L at a pressure of 0.889 atm and a temperature of 7°C. Calculate its molar mass.

120.A paper label has been lost from an old tank of compressed gas. To help identify the unknown gas, you must calculate its molar mass. It is known that the tank has a capacity of 90.0 L and weighs 39.2 kg when empty. You find its current mass to

Gas Laws Name: ___________________________ Page 16 of 17be 50.5 kg. The gauge shows a pressure of 1780 kPa when the temperature is 18°C. What is the molar mass of the gas in the cylinder?

121.What is the pressure inside a tank that has a volume of 1.20 x 103 L and contains 12.0 kg of HCl gas at a temperature of 18°C?

122.What pressure in kPa is exerted at a temperature of 20.°C by compressed neon gas that has a density of 2.70 g/L?

123.A tank with a volume of 658 mL contains 1.50 g of neon gas. The maximum safe pressure that the tank can withstand is 4.50 x 102 kPa. At what temperature will the tank have that pressure?

124.The atmospheric pressure on Mars is about 6.75 millibars (1 bar = 100 kPa = 0.9869 atm), and the nighttime temperature can be about -75°C on the same day that the daytime temperature goes up to -8°C. What volume would a bag containing 1.00 g of H2 gas have at both the daytime and nighttime temperatures?

125.What is the pressure in kPa of 3.95 mol of Cl2 gas if it is compressed in a cylinder with a volume of 850. mL at a temperature of 15°C?

126.What volume in mL will 0.00660 mol of hydrogen gas occupy at a pressure of 0.907 atm and a temperature of 9°C?

127.What volume will 8.47 kg of sulfur dioxide gas occupy at a pressure of 89.4 kPa and a temperature of 40.°C?

128.A cylinder contains 908 g of compressed helium. It is to be used to inflate a balloon to a final pressure of 128.3 kPa at a temperature of 2°C. What will the volume of the balloon be under these conditions?

129. The density of dry air at 27°C and 100.0 kPa is 1.162 g/L. Use this information to calculate the molar mass of air (calculate as if air were a pure substance).

Answers on the next page.

Gas Laws Name: ___________________________ Page 17 of 17Page 2 1. a) -250

b) 1700 K c) 37 in.d) 67 kPae) 670 mb

2. a) 110 dm3

b) 1.0 dm3

c) 130 kPaPage 31. a) 990 cm3

b) 2 dm3

c) 350 cm3

2. a) 4 dm3

b) 170 cm3

c) 9.9 x 106 cm3/dayPage 51. a) 54 kPa

b.) Omit c) 320 cm3

Handout Page 8-13

Boyle’s Law1. 8 L2. 1 L3. 130 atm4. 0.5 L5. 0.6 atm6. 490 mL7. 21000 L8. 60 mL9. 1.8 L10. decrease11. doubles12. 2.60 L13. 33 mL14. 60 mL15. 27 L16. 27 L17. 67 L18. 30 L19. 9 L

20. 300 mL21. 1.5 ft3

22. 470 mL23. 3300 L24. 7.5 atm

Charles’ Law25. decrease is 130 oC26. 680 mL27. 1200 mL28. 70 mL29. 290 mL30. 8.5 L31. 4.1 L32. 4.1 L33. 7 L34. 620 mL35. 410 mL36. 68 mL37. 30 mL38. decrease39. double40. 680 mL41. 2300 mL42. -240 oC43. 610 L44. 1.5 L45. 1.0 atm46. 0.3 atm47. 67 oC48. 634 mm Hg49. 45 oC50. 3.3 atm51. 1100 mm Hg52. 220 kPa53. 30 atm

Dalton’s law54. 9 atm55. 1.2 atm56. 65 L 57. 86 L 58. 15 mol, 20 mol,

3 atm, 35 mol

59. 470 mm Hg 60. 160 g61. 800 mL

Combined Law62. 9.5 L63. 870 mL64. 19 L65. 50 mL66. 34 mL67. 9.3 mL68. 330. mL69. -30. oC70. 2000 mL71. 10000 oC72. 93 L73. 2/3 of vol.74. 0.02 atm75. 440 mL76. 40 L77. 0.8 atm78. 790 oC79. 39 L80. 660 mL81. 360 mL82. 41 mL83. 16L84. 7 L change

pressure to kPa (200. kPa)

85. 93 mL (Take the average wvp is 24.5 mm Hg)

86. 0.95 L 87. 46 mL88. 0.04 mol 89. 4900 mm Hg90. 73 L91. 11 L92. 0.01 mol93. 3 mol94. increase (doubles)95. 29 L

96. 300 mm Hg97. 5 L98. 32 L99. 2 g/mol100. 200 mol101. 0.8 mol yes It

would have the same # of molecules.

102. 2 g103. 1 L104. 2.5 mol105. 170 oC106. 80 g/mol107. 160 g/mol108. 37 g/mol109. 6.6 g/mol110. 17 g/mol NH3

111. 2 g/mol H2 112.33.7 atm113.3.06 g/L114.663 g/mol115.204 L116.0.0101 mol 117.5.16 g NO118.77.0% yield119.10.5 g/mol120.171 g/mol121.6.55 atm122.326 kPa123.479 K or

206°C124.1210 L at -

75°C; 1620 L at -8°C

125.1.11 x 104 kPa

126.168 mL127.3.85 x 103 L128. 4.05 x 103 L129.29.0 g/mol