Dalton's Law
Examples and problems only

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Ten Examples

Example #1: 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?

Example #2: The partial pressure of F2 in a mixture of gases where the total pressure is 1.00 atm is 300. torr. What is the mole fraction of F2?

Example #3: 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?

Example #4: If 60.0 L of nitrogen is collected over water at 40.0 °C when the atmospheric pressure is 760.0 mm Hg, what is the partial pressure of the nitrogen?

Example #5: A mixture of 2 moles of H2, 3 moles of NH3, 4 moles of CO2, and 5 moles of N2 exert a total pressure of 800. torr. What is the partial pressure of each gas?

Example #6: If you place 3.00 mol of N2 and 4.00 mol of O2 in a 35.0 L container at 25.0 °C, what will the pressure of the resulting mixture of gases be?

Example #7:

Example #7: 95.0 g of CO2 and 20.0 g of Ar are placed in a rigid container and the total pressure is measured to be 1.65 atm. What is the partial pressure of each gas?

Example #8: A mixture of 14.0 grams of hydrogen, 84.0 grams of nitrogen, and 2.00 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?

Example #9: A mixture of gases contains 2.14 g of N2, 5.85 g of H2, and 4.18 g of NH3. If the total pressure of the mixture is 4.58 atm, what is the partial pressure of each component?

Example #10: 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?

Bonus Example: 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.


Probs 1 - 10

Problem #1: A mixture of 40.0 g of oxygen and 40.0 g of helium has a total pressure of 0.900 atm. What is the partial pressure of each gas?

Problem #2: If a gas is collected over water, what corrections need to be made when calculating the volume of the dry gas at STP?

Problem #3: Nitrogen is collected over water at 40.0 °C. What is the partial pressure of nitrogen if the total pressure is 99.42 kPa?

Problem #4: Three gases (8.00 g of methane, CH4, 18.0 g of ethane, C2H6, and an unknown amount of propane, C3H8) were added to the same 10.0 L container. At 23.0 °C, the total pressure in the container was measured to be 4.43 atm. Calculate the partial pressure of each gas in the container.

Problem #5: A gaseous mixture of O2 and N2 contains 32.8% nitrogen by mass. What is the partial pressure of oxygen in the mixture, if the total pressure is 785.0 mmHg?

Problem #6: A 1.50 L bulb containing He at 155 torr is connected by a valve to a 2.00 L bulb containing CH4 at 245 torr. The valve between the two bulbs is opened and the two gases mix.

(a) What is the partial pressure (torr) of He and CH4?
(b) What is the mole fraction of He?

Problem #7: A mixture of He and O2 gases used by deep-sea divers. If the pressure of the gas a diver inhales is 8.0 atm, what percent of the mixture should be O2, if the partial pressure of O2 is to be the same as what the diver would ordinarily breathe at sea level?

Problem #8: A diver breathes a helium-oxygen mixture with an oxygen mole fraction of 0.050. What must the total pressure be for the partial pressure of oxygen to be 0.21 atm?

Problem #9: A sample of 1.43 g of helium and an unweighed quantity of O2 are mixed in a flask at room temperature. The partial pressure of helium in the flask is 42.5 torr, and the partial pressure of oxygen is 158 torr. What mass of O2 is in the sample?

Problem #10: The mass percent of a three component gas sample is 22.70% O2, 21.00% C2H2F4 and 56.30% C6H6. Calculate the partial pressure (atm) of C2H2F4 if the total pressure of the sample is 1444 torr.

Problem #11: A student has stored 100.0 mL of neon gas over water on a day when the temperature is 27.0 °C. The barometer in the room reads 99.10 kPa. What is the pressure of the neon gas?


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