Unit 7: Gases
How gas particles behave according to kinetic theory, and the laws that let you predict a gas's pressure, volume, and temperature from any two.
10 topics · 34 questions
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7.1 Kinetic Molecular Theory of Gases
- How it worksHow do gas particles speed up and collide harder with the container walls as temperature rises?
- How it worksHow does the average kinetic energy of gas particles directly track the gas's temperature in Kelvin?
- Common mistakeWhy doesn't a gas particle's average speed stay the same when you heat the container?
- Going furtherWhat happens to the number of collisions per second when you squeeze the same gas into a smaller container?
- Ties togetherHow does the particle-collision picture of kinetic theory explain Boyle's law and Gay-Lussac's law?
Your turn1 of 2
A small puff of gas released into an empty room eventually spreads out to fill the entire room evenly, no matter how large that room is. Why does a gas expand to completely fill any container you put it in?7.2 Gas Pressure and How It's Measured
- How it worksHow do gas particles colliding with a surface add up to create measurable pressure?
- Worked exampleFind the pressure in atmospheres equivalent to 760 mmHg.
- Common mistakeWhy doesn't a vacuum have any gas pressure at all?
Your turn1 of 2
Find the pressure in atmospheres equivalent to 2104 mmHg.7.3 Boyle's Law
- How it worksHow does shrinking a gas's volume at constant temperature force its pressure to rise?
- Worked exampleFind the new volume of a gas that starts at 4 liters and 2 atm when the pressure rises to 8 atm at constant temperature.
- Common mistakeWhy doesn't Boyle's law apply if the gas's temperature is also changing?
Your turn1 of 2
A gas starts at 14 liters and 4.07 atm. If the pressure rises to 11 atm while the temperature stays constant, what is the new volume?7.4 Charles's Law
- How it worksHow does heating a gas at constant pressure give its particles enough energy to push the container's volume larger?
- Worked exampleFind the new volume of a gas that starts at 2 liters and 300 K when heated to 600 K at constant pressure.
- Common mistakeWhy does Charles's law require temperature to be measured in Kelvin instead of Celsius?
Your turn1 of 2
A gas starts at 10.6 liters and 280 K. When heated to 666 K while the pressure stays constant, what is the new volume?7.5 Gay-Lussac's Law
- How it worksHow does raising a gas's temperature at constant volume force its pressure to climb?
- Worked exampleFind the new pressure of a gas that starts at 1 atm and 250 K when heated to 500 K at constant volume.
- Common mistakeWhy doesn't Gay-Lussac's law describe what happens when the container is free to expand?
Your turn1 of 2
A gas starts at 5.72 atm and 280 K. When heated to 666 K while the volume stays constant, what is the new pressure?7.6 The Combined Gas Law
- How it worksHow does the combined gas law fold Boyle's, Charles's, and Gay-Lussac's laws into one equation?
- Worked exampleFind the final volume of a gas that goes from 2 L, 1 atm, and 300 K to a new state of 2 atm and 450 K.
- Common mistakeWhy doesn't the amount of gas need to stay fixed for the combined gas law to still be useful?
Your turn1 of 2
A gas goes from 11 liters, 2.77 atm, and 340 K to a new state of 2.03 atm and 225 K. Using the combined gas law, what is the final volume?7.7 Avogadro's Law and Molar Volume
- How it worksHow does adding more moles of gas at constant temperature and pressure force the volume to expand?
- Worked exampleFind the volume occupied by 2 moles of an ideal gas at standard temperature and pressure.
- Common mistakeWhy doesn't a heavier gas molecule take up more space than a lighter one at the same temperature and pressure?
Your turn1 of 2
Find the volume occupied by 13.96 moles of an ideal gas at standard temperature and pressure, where one mole occupies 22.4 liters.7.8 The Ideal Gas Law
- How it worksHow does PV equals nRT let you solve for any one gas variable if you know the other three?
- Worked exampleFind the pressure exerted by 2 moles of gas in a 10 liter container at 300 K.
- Common mistakeWhy doesn't the ideal gas law require you to know what specific gas you're dealing with?
Your turn1 of 2
Find the pressure exerted by 10.51 moles of gas in a 26 liter container at 476 K. Use R = 0.0821 L·atm per mol·K.7.9 Dalton's Law of Partial Pressures
- How it worksHow does each gas in a mixture contribute its own partial pressure that adds up to the total?
- Worked exampleFind the total pressure of a container holding oxygen at 2 atm and nitrogen at 3 atm.
- Common mistakeWhy doesn't one gas in a mixture somehow block another gas from contributing its own pressure?
Your turn1 of 2
Find the total pressure of a sealed container holding one gas at 7.02 atm and a second gas at 6.56 atm.7.10 Real Gases and Why They Deviate from Ideal
- How it worksHow do the actual volume of gas particles and the attraction between them break the ideal gas assumptions?
- How it worksHow do intermolecular attractions matter more for a real gas at low temperature than they do at high temperature?
- Common mistakeWhy doesn't every gas behave ideally at very low temperatures close to where it condenses?
- Going furtherWhat happens to a real gas's behavior as its pressure gets low and its temperature gets high?
- Ties togetherHow does intermolecular attraction explain why the ideal gas law is only an approximation for real gases?
Your turn1 of 2
At ordinary room pressure, a real gas behaves very close to what the ideal gas law predicts, but as that same gas is squeezed under increasingly high pressure, its actual behavior starts drifting noticeably away from the ideal prediction. Why does a real gas behave less like the ideal gas law predicts as you squeeze it under high pressure?