Combined+Gas+Law.dj

Often times a gas sample undergoes a change in temperature, pressure, and volume at the same time. When this happens they must all be dealt with at once. The combined gas laws deals with this by combining Boyle's law, Charles's law, and Gay-Lussac's law, all combined into one equation. This law expresses the relationship between pressure, volume, and temperature of a fixed amount of gas. The equation for this law looks like: (P1)(V1) / T1= (P2)(V2) / T2. The P1 stands for pressure, and the P2 stands for a different pressure, which is the same for V1 V2 and T1 T2.

A helium filled balloon has a volume of 50.0 L at 25ºC and at 1.08 atm. What volume will it have at .855atm and 10.0ºC?
 * Example Problem:**

__Step One__: Given: V1 of He = 50L ; T1of He = 298K ; T2 of He = 283K ; P1 of He = 1.08atm ; P2 of He = 0.855atm Looking For: V2 of He in L

__Step Two:__ Rearange the equation in order to solve for V2: V2 = (P1)(V1)(T2) / (P2)(T1)

__Step Three__: Substitute the values for the equation V2 = (1.08atm)(50L He)(283K) / (0.855atm)(298K) = 60L He

The pressure decreases more than the temperature decreases. The net result of two changes gives an increase in the volume from 50L to 60L. Home Page
 * Conclusion:**