Gases are a state of matter that has very low density, can be compressed and has a set volume at all times. Matter in the gaseous state can be transformed into any of the other states of matter.
The ideal gas law is a combination of three other gas laws: Boyle's law, Charles's Law and Gay-Lussac's law. The ideal gas law describes the fundamental relationships of a perfect gas. The formula used relates quantity, pressure, temperature and volume. The formula for the ideal gas law looks like this:
PV = nRT
"P" represents pressure in pascals, "V" represents volume in liters, "n" is the number of moles, "R" is a constant called the universal gas constant, and "T" is temperature in Kelvin. The universal value for "R" is equal to 8.3145 Joules/mole Kelvin.
In the previous equation "n" is the measurement of the quantity of gas. In chemistry this measurement is called moles. Moles is the decimal percentage of how many of 6.02E23 parts exist in a given sample. Meaning if you have 5.00E22 parts, then you have about 0.083 moles. Parts are either single atoms or whole molecules of large compounds.
In the ideal gas law, pressure, represented as "P," is the measurement of the pressure exerted on the gas. This equation measures pressure in pascals. Typically, pressure is measured using other variables. More popular is the millibar, often used to describe the pressure in the atmosphere. Converting from millibars to pascals is easy. One-hundred pascals are equal to exactly 1 millibar.
"T" is the temperature of the gas, measured in Kelvin. Kelvin is a temperature scale that does not have negative values, like Celsius and Fahrenheit do. Converting to Kelvin is easy. All you have to do is add 273 to your Celsius value. To convert from Fahrenheit to Kelvin use the following equation:
(9/5)*(x)+305
In this equation, insert your Fahrenheit value into "x."
As you can probably see by now,there is an obvious relationship between temperature, pressure and quantity. When you increase one value, some of the other values will have to decrease. This means that if you decrease the temperature of a gas, either the pressure, moles, volume, or a combination of the three will decrease to maintain equilibrium. Since "R" is a constant, it is not affected by change.
Volume is most often changed in nature by altering pressure and temperature. This can be seen specifically with weather systems. The air is much denser in high-pressure systems. The number of air molecules stays the same, but the volume in which the air is being held will decrease. Using the ideal gas law, you can expect this to happen. At the same time, increases in the temperature will cause a decrease in density and then an increase in volume.