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Behavior of Gases

Behavior of Gases. Objective 1: What is a gas?. A state of matter where the particles are extremely spread out and as a result have no definite shape nor volume but assumes the shape of the container. . Objective #2: What is pressure?.

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Behavior of Gases

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  1. Behavior of Gases

  2. Objective 1: What is a gas? • A state of matter where the particles are extremely spread out and as a result have no definite shape nor volume but assumes the shape of the container.

  3. Objective #2: What is pressure? • Pressure is defined as the result of force distributed over an area.

  4. Objective #3: What are the variables that affect gas pressure? • Number of Particles • Temperature • Volume

  5. Objective #4: What is Boyle’s Law? • A gas law that describes the relationship between pressure and volume • The law infers that pressure and volume and inversely proportionate • Conditions: Number of particles and temperature must remain constant

  6. Boyle’s Law Practice Problems • If I have 5.6 liters of gas in a piston at a pressure of 1.5 atm and compress the gas until its volume is 4.8 L, what will the new pressure inside the piston be?

  7. Boyle’s Law Practice Problems 2. I have added 15 L of air to a balloon at sea level (1.0 atm). If I take the balloon with me to Denver, where the air pressure is 0.85 atm, what will the new volume of the balloon be?

  8. Objective #4: What is Boyle’s Law? • Formula: P1V1 = P2V2 • Left side represents variables before a phase change/ right side represents variables after the phase change. • SI Units for pressure are the “Pascals (P)”

  9. Boyle’s Law Practice Problems 3. I’ve got a car with an internal volume of 12,000 L. If I drive my car into the river and it implodes, what will be the volume of the gas when the pressure goes from 1.0 atm to 1.4 atm?

  10. Objective #5: What is Charles’ Law? • A gas law that describes the relationship between temperature and volume of gases. • The law infers that volume and temperature are directly proportionate • Conditions: Number of particles and pressure must remain constant.

  11. Objective #5: What is Charles’ Law? • Formula: V1/T1= V2/T2 • Left side represents variables before a phase change/ right side represents variables after the phase change.

  12. Charle’s Law Practice Problems • If I have 45 liters of helium in a balloon at 250 C and increase the temperature of the balloon to 550 C, what will the new volume of the balloon be?

  13. Charles’ Law Practice problems 2. Calcium carbonate decomposes at 12000 C to form carbon dioxide and calcium oxide. If 25 liters of carbon dioxide are collected at 12000 C, what will the volume of this gas be after it cools to 250 C?

  14. Objective #6: What is “Gay-Lussac’s” Law? • A gas law that describes the relationship between pressure and temperature of the gases. • The law infers that Pressure and Temperature are directly proportionate

  15. Practice Problems • Determine the pressure change when a constant volume of gas at 1.00 atm is heated from 20.0 °C to 30.0 °C. • A gas has a pressure of 0.370 atm at 50.0 °C. What is the pressure at standard temperature?

  16. Objective #6: What is “Gay-Lussac’s” Law? • Formula: P1/T1 = P2/T2 • Conditions: Volume and # of Particles must be held constant. • Remember Temperature must be in Kelvins to solve these problems. • Examples: Tire pressure and pressure cookers

  17. Objective #7: What is the Combined Gas Law? • A gas law that describes the relationship between pressure, volume & temperature of an enclosed gas • This law is a combination of the above three laws

  18. Objective #7: What is the Combined Gas Law? • Formula: (P1)(V1)/T1 x (P2)(V2)/T2 • Beneficial because it allows you to be able to solve problems when two variables are changing.

  19. Practice Problems • If I initially have 4.0 L of a gas at a pressure of 1.1 atm, what will the volume be if I increase the pressure to 3.4 atm? • A toy balloon has an internal pressure of 1.05 atm and a volume of 5.0 L. If the temperature where the balloon is released is 200 C, what will happen to the volume when the balloon rises to an altitude where the pressure is 0.65 atm and the temperature is –150 C?

  20. What is the ideal gas law? • The word ideal implies a “desired” state and doesn’t necessary mean that it is an actual state. • In this respect, the law says that the gas will obey all of the gas laws under all conditions. • This means that it doesn’t condense when cooled • The collisions within the system are totally inelastic

  21. What is the ideal gas law? • In reality, there are no gases that meet these conditions; however, we simply use the same calculations for simplification purposes. • Formula: PV = nRT R=8.31 (kPa)(L)/(K) (mol) • The R constant was pre-calculated for us.

  22. Practice Problems • How many moles of gas does it take to occupy 120 liters at a pressure of 2.3 atmospheres and a temperature of 340 K? • If I have a 50 liter container that holds 45 moles of gas at a temperature of 2000 C, what is the pressure inside the container?

  23. What is the ideal gas law? • Variables: Pressure, volume, number of moles, gas constant, and temperature. • Given three of the variables, you should be able to solve for the unknown.

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