Basic Concepts to Know
Volume - Volume refers to the space matter occupies, and is measured in liters. The volume of 1 mole of any gas at STP (standard pressure and temperature) is 22.4 liters. The volume of 1 mole of solid carbon dioxide is 28 cm3, which is not much bigger than a large ice cub. However, the same number of carbon dioxide molecules, as a gas, occupies 25000 cm3, a volume almost 1000 times grater. Only a small fraction of the total volume of the gas is occupied by the molecules themselves. The rest of the volume is empty space. Thus, there is a lot of room for the molecules to move closer together - by compression. When a gas is compressed, the same number of particles can now occupy a different volume and if that volume is decreased the pressure increases and vice versa. This is so because of when the volume decreases so does the inside surface area so the molecules can now exert more pressure on a concentrated area.
Temperature - Gas temperature is measured in degrees Kelvin, or Celsius. Realizing that temperature is the measure of the average kinetic energy, imagine some ping-pong balls confined to a box. When the ping-pong balls have little energy, they don't move very fast. However when the temperature, kinetic energy, is increased, the ping-pong balls move at a much faster pace. The average kinetic energy of a gas is 3/2*R*T, where R = 8.315 J Mol/Kelvin. The average velocity of a gas molecule can be derived from the physics equation, KE = 1/2*m*v2 = 3/2*R*T So, the velocity of a gas molecule is equal to the square root of 3*R*T/M, Where M is the molar mass of the gas in kilograms.
Pressure - Pressure can be defined as the force which acts on an object due to a gas. The SI unit for pressure is the pascal (N/m2). Other measurements for pressure are the standard atmosphere and the torr, where 101,325 Pa = 1 atmosphere (atm) = 760 torr. Any gas inside a container which has kinetic energy will exert a pressure on the outer walls of that container by colliding and rebounding due to the random motion of gases. An increase in the number of collisions per second or an increase in the force of the collisions will increase the pressure exerted by the gas on the container. Again, consider the ping-pong ball scenario. As the box is put into motion, the balls fly around randomly in all directions. If you put your hands on the outside, you will feel this. Each time one ball rebounds, there is a force exerted on the box. Each rebound represents a pressure exerted by a gas molecule. Now, if we add more ping-pong balls moving at the same speed, the pressure will increase because there are now more balls inside the container to exert force within a target area as opposed to the box with few ping-pongs. More collisions with in the target area occur per second because there are more balls moving in the same volume. What if instead of increasing the number of balls, we decide to increase the kinetic energy of the balls? The gas equivalent of increasing kinetic energy would be increasing the temperature. The gain kinetic energy causes an speed, and therefore the collisions would be stronger than before. The pressure exerted would be greater. What if the container was elastic, instead of being a rigid box? Well, an increase in pressure would cause the pressure on the inside of the container to be greater than the outside of the container. To compensate for this, the container would inflate like a balloon until the pressure on the outside was the same inside. The opposite would occur if the pressure decreased.
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Conversion Table
Abbreviations
Basic concepts 
A Sample Test 
The Glossary
PV = C V/n = C P/n = C V/T = C
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Answers to Sample Test