Chapter 13: Practice #2 (Gen) Name: ________________________________ Combined Gas Law & Dalton’s Law of Partial Pressures Combined Gas Law: relationship between volume, Kelvin temperature, & pressure Write the equation for the Combined Gas Law and label the variables:

1) A sample of chlorine gas occupies 9.2 L at 45oC and 1.3 atm. What would be the pressure when the volume is reduced to 7.8 L at 38oC? 1.5 atm 2) A gas at 110 kPa and 30.0oC fills a flexible container with an initial volume of 2.00 dm3. If the temperature is raised to 80.0oC and the pressure increases to 440 kPa, what is the new volume in dm3? (Hint: a dm3 is the same thing as a Liter) 0.58 dm3

3) A balloon containing 6200 mL helium rests in a room at 56oC and 812 mmHg. What would be volume of the balloon in mL if the temperature of the room was increased to 67oC and the pressure to 842 mmHg? 6179 mL 4) A 5.00 L air sample has a pressure of 107 kPa at a temperature of -50oC. If the temperature is raised to 102oC and the volume expands to 7.00 L, what will the new pressure be? 128.52 kPa

Dalton’s Law of Partial Pressures: the total pressure exerted by a mixture of gases is equal to the sum of

the partial pressures of the individual gases

Write the equation for Partial Pressures and label the variables:

Type A: Individual Gas Pressures Given 5) A tank contains N2 at 1.4 atm and O2 at 2.2 atm. Helium is added to this tank until the total pressure is 5.9 atm. What is the partial pressure of the helium? 2.3 atm 6) The total pressure of an O2-Ar-He gas mixture is 644 mmHg. If the partial pressure of Ar is 183 mmHg and the partial pressure of He is 375 mmHg, what is the partial pressure of O2? 86 mm Hg

7) Industrial deep-sea divers must breathe a mixture of He and O2 to prevent a disorienting condition known as nitrogen narcosis. If a diver’s tank is filled with a helium-oxygen mixture to a pressure of 184 atm and the partial pressure of helium is 129 atm, what is the partial pressure of the oxygen? 55 atm 8) A mixture of neon and argon gases exerts a total pressure of 189 kPa. The partial pressure of the neon alone is 82 kPa, what is the partial pressure of the argon? 107 kPa

Type B: Percentage of Gases Given 9) What partial pressure of oxygen is a scuba diver breathing if the total pressure is 5.8 atm and 34% of the air is oxygen? 1.97 atm 10) The air pressure in a greenhouse is 139.0 mmHg. What is the partial pressure of water vapor if it comprises 18% of the air mixture? 25.02 mmHg

11) A mixture of gases with a pressure of 753.0 mmHg contains 70% nitrogen and 30% oxygen by volume. What is the partial pressure of oxygen in this mixture? 225.9 mmHg 12) The barometer shows the atmospheric pressure to be 762 mmHg. What is the partial pressure of nitrogen if air is composed of 21% oxygen and 78% nitrogen? 594.36 mmHg

Understanding Gases 13)

Cylinder A contains 300 mL of a gas. If the temperature of cylinder A is doubled and pressure remains constant at 1 atm, what will be the new volume of the gas (cylinder B)? ______600 mL______

Explanation: As temperature increases, volume increases. Because T and V have a direct relationship, if temperature doubles, then volume doubles also.

15)

Which diagram best represents a gas in a closed container? Explanation: Gases are in constant, rapid, random motion. They diffuse or spread to fill their containers. (They do NOT settle to one end of their container.)

14)

Which graph best represents the relationship between pressure and volume as represented in the graphic?

(A) (B) (C) Explanation: As pressure increases, volume decreases (inverse relationship).

16) A sample of H2 gas and a sample of N2 gas at STP contain the same number of molecules. Each same must have… A) B) C) D)

the same volume, but a different mass the same mass, but a different volume both the same volume and the same mass neither the same volume nor the same mass

Explanation: Avogadro said that 1 mole of any gas at STP will have a volume of 22.4L. BUT different gases have a different molar mass.