On a piece of paper, write the answers that would fill in the blanks. After you have completed that, you can highlight the paragraph to reveal the answers.

John **Dalton **was the first to form a hypothesis about partial **pressure **of combined gases. After experimenting with gases, he concluded that each gas exerts the same pressure it would if it **alone **were present at the same temperature. If a gas is collected over water, the pressure in the container actually includes the sum of the vapor **pressure **of the gas and the **water **vapor pressure. Consequently, we must **subtract **the water vapor pressure from the total pressure to obtain the pressure of the **gas **alone.

Avogadro’s law states that equal volumes of different gases, at the same **temperature **and **pressure**, contain the same **number **of **molecules**.

Word Bank:

gas pressure (used 3 times) subtract molecules Dalton temperature water number alone

Using the formulas that you learned, work the following problems. Determining which gas law problem to use is the key. Do this by labeling the data given, identifying the data that the problem is looking for, and matching those things to the different gas laws. Refer to your gas laws formula sheet as a reference.

To check the solutions to the problems, click on *Step 1*, *Step 2*, and then *Step 3* for explanations.

1. A 952 cm^{3} container of gas is exerting a pressure of 108 kPa while at a temperature of 48 °C. Calculate the pressure of this same amount of gas in a 1236 cm^{3} container at a temperature of 64 °C.

2. At STP, a sample of gas occupies 24.5 mL. Calculate the volume of this gas at a pressure of 2.3 atm and a temperature of 221 K.

3. A 3.25 L container of ammonia gas exerts a pressure of 652 mm Hg at a temperature of 243 K. Calculate the pressure of this same amount of gas in a 2.50 L container at a temperature of 311 K.

4. A sample of gas has a volume of 5.23 cm^{3} at a pressure of 72.6 kPa and a temperature of 25 °C. What will be the volume of the gas if the pressure is changed to 124 kPa and the temperature is changed to 0 °C?

5. Calculate the pressure (in kPa) of 0.421 mole of helium gas at 254 K when it occupies a volume of 3.32 L.

6. How many moles of argon are there in a 22.4 L sample of gas at 101.3 kPa and 0 °C?

7. What is the volume of 2.56 moles of gas at 0.634 atm and 65 °C?

8. A 500.0 g block of dry ice (solid CO_{2}, molar mass = 44.0 g) vaporizes to a gas at room temperature. Calculate the volume of gas produced at 25.0 °C and 1.50 atm.