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Chemistry Honors Vocabulary » Gases
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Gases
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Gas = state of matter with no definite shape or volume STP = standard temperature (0 degress Celsius) and standard pressure (1 atm = 101.3 kPa = 760 mmHg = 760 torr) Boyle's Law: The volume of a gas at constant temperature varies inversely with pressure. In other words, if you put big pressure on something, it gets small. Charles's Law: The volume of a gas at constant pressure is directly proportional to the temperature. In other words, if you heat something up, it gets big. temperature: A measurement of the average kinetic energy of the particles in a system. Kelvin: A unit used to measure temperature. One Kelvin is equal in size to one degree Celsius. To convert between degrees Celsius and Kelvins, simply add 273.15 to the temperature in degrees Celsius to get Kelvins ideal gas law: PV=nRT ideal gas: A gas in which the particles are infinitely small, have a kinetic energy directly proportional to the temperature, travel in random straight lines, and don't attract or repel each other. Needless to say, there's no such thing as an ideal gas in the real world. However, we use ideal gases anyway because they make the math work out well for equations that describe how gases behave. partial pressure: The pressure of one gas in a mixture. For example, if you had a 50:50 mix of helium and hydrogen gases and the total pressure was 2 atm, the partial pressure of hydrogen would be 1 atm. diffusion: When particles move from areas of high concentration to areas of low concentration. For example, if you open a bottle of ammonia on one end of the room, the concentration of ammonia molecules in the air is very high on that side of the room. As a result, they tend to migrate across the room, which explains why you can smell it after a little while. Be careful not to mix this up with effusion effusion: When a gas moves through an opening into a chamber that contains no pressure. Effusion is much faster than diffusion because there are no other gas molecules to get in the way. Graham's Law = The lighter the gas, the faster it will move. Real Gas = a gas that does not behave completely according to the assumptions of the KMT molar volume: The volume of one mole of a substance at STP. If you believe that everything is an ideal gas, this is always 22.4 liters.
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