Chemistry I – Problem Set #1
Pressure/Temperature/Volume
· Convert the following pressures/temperatures/volumes.
· CIRCLE YOUR ANSWERS and express answers in correct sig figs and unit.
1. Convert the following pressures to atm:
1
a. 350 kPa
b. 121.0 kPa
c. 780.0 mmHg
d. 1600mmHg
1
2. Convert the following pressures to kPa:
1
a. 2.00 atm
b. 880 mmHg
c. 0.950 atm
d. 1200.0 mmHg
1
3. Convert the following pressures to mmHg:
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a. 0.500 atm
b. 1.25 atm
c. 250.0 kPa
d. 150 kPa
e. 3.25 atm
f. 85.5 kPa
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4. Convert the following temperatures:
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a. 500.0 K à ºC
b. -29 ºC à K
d. 45.0 ºC à K
e. 225 K à ºC
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c. 27.00 ºC à K f. 125.0 ºC à K
5. Convert the following volumes:
a. 2.50 L à mL
b. 7500 mL à L
c. 250. mL à L
d. 0.450 L à mL
e. 500. mL à cm3
f. 56780 mL à L
g. 35 mL à L
h. 0.015 L à mL
i. 0.850 L à cm3
Chemistry I – Problem Set #2
Boyles Law
Boyle’s Law states that the volume of a gas varies inversely with its pressure if temperature is held constant. (If one goes up, the other goes down). We use the formula:
P1V1 = P2V2
Solve the following problems (assuming constant temperature).
You must write the equation. Circle your answer!
1. A sample of oxygen gas occupies a volume of 250 ml at 740 torr pressure. What volume will it occupy at 800. torr pressure?
2. A sample of carbon dioxide occupies a volume of 3.50 liters at 125 kPa pressure. What pressure would the gas exert if the volume was decreased to 2500. mL?
3. A 2.0 liter container of nitrogen had a pressure of 3.2 atm. What volume would be necessary to decrease the pressure to 105.6 kPa?
4. Ammonia gas occupies a volume of 450 ml at a pressure of 720 mm Hg. What volume will it occupy at standard pressure?
5. A 175 mL sample of neon had its pressure changed from 720.5 mmHg to 150 kPa. What is its new volume?
6. A sample of hydrogen at 1.5 atm had its pressure decreased to 0.50 atm producing a new volume of 750 mL. What was its original volume?
7. Chlorine gas occupies a volume of 1.2 liters at 720 mmHg pressure. What volume will it occupy at standard pressure?
8. Fluorine gas exerts a pressure of 900. torr. When the pressure is changed to 1.50 atm, its volume is 250 mL. What was the original volume?
Chemistry I – Problem Set #3
Charles’ Law
Charles’ Law states that the volume of a gas varies directly with the Kelvin temperature, assuming that pressure is constant. We use the formula:
V1T2 = V2T1 and K = °C + 273
Solve the following problems (assuming constant pressure). Circle your answer!
1. A sample of nitrogen occupies a volume of 250 mL at 25.0°C. What volume will it occupy at 95.5°C?
2. Oxygen gas is at a temperature of 40.5°C when it occupies a volume of 2.3 liters. To what temperature should it be raised to occupy a volume of 6.5 liters?
3. Hydrogen gas was cooled from 150.5°C to 50.0°C. Its new volume if 75.0mL. What was its original volume?
4. Chlorine gas occupies a volume of 25.0mL at 300.0K. What volume will it occupy at 600.0 K?
5. A sample of neon gas at 50.5°C and a volume of 2.55 liters is cooled to 25.5°C. What is the new volume?
6. Fluorine gas at 27.5°C occupies a volume of 500.0 mL. To what temperature should it be lowered to bring the volume to .300 L?
7. Helium occupies a volume of 3.8 liters of -45°C. What volume will it occupy at 45.0°C?
8. A sample of argon has is cooled and its volume went from 380 mL to 250 mL. If its final temperature was 35.5°C, what was its original temperature?
Chemistry I – Problem Set #4
Combined Gas Law
In practical terms, it is often that we look at changes in pressure, volume and temperature. We use the combined gas law when doing so.
P1V1T2 = P2V2T1
P1 / V1 / T1 / P2 / V2 / T21 / 1.5 atm / 3.0 L / 20°C / 2.5 atm / 30°C
2 / 720 torr / 256 mL / 25°C / 250 mL / 50°C
3 / 600 mmHg / 2.5 L / 22°C / 760 mmHg / 1.8 L
4 / 750 mL / 0°C / 2.0 atm / 500 mL / 25°C
5 / 95 kPa / 4.0 L / 101 kPa / 6.0 L / 471 K or
198°C
6 / 650 torr / 100°C / 900 torr / 225 mL / 150°C
7 / 850 mmHg / 1.5 L / 15°C / 2.5 L / 30°C
8 / 125 kPa / 125 mL / 100 kPa / 100 mL / 75°C
Solve each of the following equations using the combined gas law. SHOW ALL WORK!
1. If you initially have a gas at a pressure of 12.0 atm, a volume of 23.5 liters, and a temperature of 200. K, and you increase the pressure to 14.0 atm and increase the temperature to 300. K, what is the new volume of the gas?
2. A gas takes up a volume of 17.5 liters, has a pressure of 2.31 atm, and a temperature of 299 K. If the temperature is increased to 350 K and the pressure is decreased to 1.75 atm, what is the new volume of the gas?
3. A gas that has a volume of 2500 mL, a temperature of 45º C, and an unknown pressure has its volume increased to 34 liters and its temperature decreased to 35º C. If the pressure of the gas after the change is 980 mmHg, what was the original pressure of the gas?
4. A sample of oxygen gas has a temperature of 14.5 º C, a volume of 500. mL, and a pressure of 850.0 torr. What would be the new volume of the oxygen at STP?
5. If 17.5 liters of neon gas is at a temperature of 67 º C and a pressure of 1500 mmHg, what will be the new temperature of the gas if the pressure is decreased to 1100 mmHg and the volume is decreased to 15.0 liters?
6. An unknown volume of gas is at a pressure of 0.500 atm and a temperature of 110. º C. If the temperature is decreased to 85.0 º C, the pressure increased to 1.75 atm, and the final volume is 20.0 liters, what was the original volume of the gas?
7. A gas company has a 21 liter sample of ethanol at a pressure of 790 torr and a temperature of 50.0 º C. What would be the new volume of the ethanol at STP?
8. A 2900 mL container of dinitrogen tetroxide is at a pressure of 5.00 atm and a temperature of 24.5 º C. If the temperature was increased to 75.5 º C and the volume measured 3.5 liters, what is the new pressure?
9. An unknown gas is held in a 75 liter container at 945 mmHg. If the conditions are changed to standard and the volume is decreased to 65.5 liters, what was the original temperature of the sample?
Chemistry I – Problem Set #5
Boyles/Charles/Combined Gas Law
· Determine which of the gas laws is required to solve each of the following problems. Show all work, express answers in correct sig figs and units, and circle answers.
9. A sample of gas occupies 75.0 mL at 725 mmHg and 18.0º C. Calculate its volume at 800. mmHg and 25.0º C.
Gas Law______
10. A container of iodine gas occupies a volume of 3750 mL at 95.15 kPa and 27.5º C. At what temperature will the sample occupy 4.00 liters if the pressure remains constant?
Gas Law______
11. A sample of butane gas occupies 8.25 liters at STP. What will be the new volume of the sample if the conditions are changed to 735 mmHg and 20.0º C?
Gas Law______
12. Chlorine gas occupies 0.575 liters at 1.50 atm and 125º C. At what pressure will the volume be 0.300 liters if the temperature remains constant?
Gas Law______
13. Oxygen gas occupies 2300 mL at 825 torr and 70.0º C. What is its new volume at STP?
Gas Law______
14. An 8500 mL tank of gas has a pressure of 200.75 kPa and 20.0º C. What will be the new temperature if its volume is reduced to 6500 mL and the pressure is increased to 250.00 kPa?
Gas Law______
15. A 250 mL flask of gas is at 785 torr of pressure and 25.5º C. what will be the pressure of the gas if it is cooled to 0.00º C and now occupies 100. mL?
Gas Law______
16. An open 50.0 liter tank of gas if filled to a pressure of 120.0 kPa at 10.0º C, what will be its new volume when the pressure increases to 150. kPa but there is no change in temperature?
Gas Law______
17. 5500 mL of hydrogen gas is at STP. What will be the new volume of the sample if the temperature is increased to 75.0º C and the pressure remains constant?
Gas Law______
18. The temperature of a container of gas whose pressure is 650 torr is changed from 40.0º C to 140.0º C. What will be the new pressure?
Gas Law______
19. An equal mixture of oxygen and hydrogen gases is held in a 250. liter container at 97.5 kPa and 30.0º C. What would be the new volume if the conditions were changed to STP?
Gas Law______
Chemistry I – Problem Set #6
Ideal Gas Law
· Use the ideal Gas Law below to answer the following questions.
PV = nRT where P = pressure in atms V = volume in liters
n= number of moles T = temperature in Kelvins
R = universal gas constant (0.0821 L●atm/mol●K)
1. How many moles of oxygen will occupy a volume of 2.5 liters at 1.2 atm and 25°C?
2. What volume will 2.0 moles of nitrogen occupy at 720 torr and 20°C?
3. What pressure will be exerted by 25 g of CO2 at a temperature of 25°C and a volume of 500ml?
4. At what temperature will 5.00 g of Cl2 exert a pressure of 900 torr at a volume of 750 ml?
5. What is the density of NH3 at 800 torr and 25°C?
6. If the density of a gas is 1.2g/L at 745 torr and 20°C, what is its molecular mass?
7. How many moles of nitrogen gas will occupy a volume of 347 mL at 6680 torr and 27°C?
8. What volume will 454 grams (1 lb) of hydrogen occupy at 1.05 atm and 25°C?
9. Find the number of grams of CO2 that exert a pressure of 785 torr at a volume of 32.5 L and a temperature of 32°C?
10. An elemental gas has a mass of 10.3g. If the volume is 58.4L and the pressure is 758 torr at a temperature of 2.5°C, what is the gas?
11. Determine the number of moles for each of the following substances:
a. 5.75 x 1026 molecules of oxygen gas
b. 75 grams of helium gas
c. 250 grams of bromine gas
d. 3.575 x 1024 molecules of iodine gas
e. 700. grams of dinitrogen tetroxide
12. What is the volume at STP occupied by 8.25 x 1024 molecules of oxygen gas?
13. What is the number of moles of nitrogen gas present in 675 mL at STP?
14. A 2.50 x 1022 molecule sample of nitrogen monoxide gas occupies a volume of 20.0 liters. If the pressure of the sample is 1200.0 torr, what is the temperature?
15. What is the volume of 175 grams of bromine gas at 1.50 atm of pressure and a temperature of 27.0º C?
16. A 340 gram sample of iodine gas occupies a volume of 50.0 liters at a temperature of 95.0 º C. What is the pressure of the sample in mmHg? (solve for pressure of atm and then convert to mmHg)
17. How many molecules of carbon dioxide gas are there in 2800 mL at STP? (solve for moles first and then convert to molecules)
18. What is the pressure of 75.0 grams of neon gas in a 5500 mL container at 75.0º C?
19. 2.5 moles of nitrogen dioxide gas is in a 500. mL tank at 120 kPa of pressure. What is the temperature in degrees Celsius? (find the temp in K first and then convert to C)
20. How many molecules of sulfur trioxide are in a 5000. mL container at a pressure of 850 torr and a temperature of 50.0º C? (solve for moles first and then convert to molecules)
Chemistry I – Problem Set #7
Mixed Gas Laws
*Show all work, express answers in correct sig figs, and units. Circle all answers.
1. Helium in a 100. mL container at a pressure of 66.5 kPa is transferred to a container with a volume of 250 mL.
A) What is the new pressure if no change in temperature occurs?
B) What is the new pressure if the temperature changes from 20.0° C to 15.5° C?
2. If a steel cylinder with a volume of 1.50 L contains 10.0 moles of oxygen, under what pressure is the oxygen if the temperature is 27.5° C?
3. What will have to happen to the temperature of a sample of methane if 1000. mL at 98.6 kPa and 25.0° C occupies a new volume of 900. mL with no change to the pressure?
4. A oxygen gas has a volume of 225 mL at 75.0° C and 175 mmHg. What will be its volume at a temperature of 20.0° C and a pressure of 11000 mmHg?
5. A gas is heated to 80.0° C and a pressure of 180 kPa. If the container expands to hold a volume of 800. mL, what was the volume of the gas at a temperature of 50.0° C and 930 mmHg pressure?
6. How many liters of nitrogen, N2, would have to be collected at 99.19 kPa and 28.0° C to have a sample containing 35.8 grams of N2?
7. A 200. mL sample of bromine gas is collected at 50.0 kPa and a temperature of 271° C. What volume would this gas occupy at STP?
8. A balloon is to be filled with 175 grams of helium gas. What volume can be filled to a pressure of 1.15 atm if the temperature is 20.0° C?
9. A gas has a volume of 55.5 mL at 45.0° C and 85.0 kPa. What will be its volume if air pressure remains constant and temperature rises to 95.0° C?