Gas Laws and Measurements

In this video, Miss KY explains Dalton's Law of Partial Pressure, focusing on the concept of water vapor pressure when collecting gas over water. Two problems are solved using the combined gas law, demonstrating how to adjust for water vapor pressure to find the pressure of dry gas. The video emphasizes the importance of correcting for water vapor pressure in calculations and concludes with a reminder of key points.

What is the key concept to remember when collecting gas over water?

• The gas pressure is equal to the atmospheric pressure.

• The gas pressure is independent of water vapor pressure.

• The gas pressure is the sum of the gas and water vapor pressures.

• The gas pressure is only the water vapor pressure.

In the first problem, what is the initial pressure of the gas collected over water?

• 760 mmHg

• 823.3 mmHg

• 300 mmHg

• 850 mmHg

What is the corrected pressure of the dry gas in the first problem?

• 300 mmHg

• 760 mmHg

• 823.3 mmHg

• 850 mmHg

What is the volume of the dry gas at STP in the first problem?

• 50.0 mL

• 125 mL

• 49.3 mL

• 84.2 mL

In the second problem, what is the initial pressure of the oxygen gas collected over water?

• 942.44 mmHg

• 1 atm

• 1.24 atm

• 760 mmHg

What is the water vapor pressure at 75°C in the second problem?

• 760 mmHg

• 26.7 mmHg

• 89.1 mmHg

• 289.1 mmHg

What is the corrected pressure of the dry gas in the second problem?

• 942.44 mmHg

• 760 mmHg

• 652.9 mmHg

• 1 atm

What is the volume of the dry gas at STP in the second problem?

• 125 mL

• 84.2 mL

• 49.3 mL

• 50.0 mL

Why is it important to subtract the water vapor pressure when using the combined gas law?

• To ensure the gas pressure is not overestimated.

• To decrease the volume of the gas.

• To change the temperature of the gas.

• To increase the total pressure.

What is the standard temperature in Kelvin used in these problems?

• 0 K

• 273 K

• 348 K

• 300 K