1. Combined Gas Law
Chapter 14

2. Combined Gas Law So far we have seen 3 gas laws:
Boyles Law: P1V1 = P2V2
Charles Law: V1 = V2
T1 T2
Lussac’s Law: P1 = P2
T1 T2

3. Combined Gas Law These are all subsets of a more encompassing law:
The Combined Gas Law
P1V1 = P2V OR P1V1T2 = P2 V2T1
T T2
Of the 3 states of matter, gases may have the most unusual, yet consistent set of properties. For example, we know that ALL gases occupy approximately the same volume per mole under conditions of STP. The problem comes in arriving at a volume for a given number of moles or mass of gas if conditions are not at STP.

4. Applications of the Combined Gas Law
opening a soda can - At the bottling plant, high-pressure carbon dioxide is added to the head space in order to ensure that more CO2 will be absorbed into the soda itself. The higher the pressure of the CO2 in the head space, the greater the amount of CO2 in the drink itself; and the greater the CO2 in the drink, the greater the "fizz" of the soda. Once the container is opened, the pressure in the head space drops dramatically. Over a period of time, the soda will release that gas, and will eventually go "flat."

5. Applications of the Combined Gas Law
fire extinguishers - Inside the cylinder is a tube of carbon dioxide surrounded by a quantity of water, which creates pressure around the CO2 tube. A siphon tube runs vertically along the length of the extinguisher, with one opening near the bottom of the water. The other end opens in a chamber containing a spring mechanism attached to a release valve in the CO2 tube. The water and the CO2 do not fill the entire cylinder. When the operating lever is depressed, it activates the spring mechanism, which pierces the release valve at the top of the CO2 tube. When the valve opens, the CO2 spills out in the "head space," exerting pressure on the water. This high-pressure mixture of water and carbon dioxide goes rushing out of the siphon tube, which was opened when the release valve was depressed. All of this happens, of course, in a fraction of a second—plenty of time to put out the fire.

6. Applications of the Combined Gas Law
aerosol cans - include a nozzle that depresses a spring mechanism, which in turn allows fluid to escape through a tube. Most of the can's interior is made up of the product mixed with a liquid propellant. The "head space" of the aerosol can is filled with highly pressurized propellant in gas form, when the nozzle is depressed, the pressure of the propellant forces the product out through the nozzle.

7. Combined Gas Law Practice I
1. A gas at 110 kPa and 30°C fills a flexible container with an initial volume of 2.O L. If the temperature is raised to 80°C and the pressure is increased to 440 kPa, what is the new volume?
To Solve Combined Gas Law Problems:
Convert temperatures into Kelvin Scale
Plug in numbers/solve
P1V1 = P2V T1 T2
3. Be sure your answer makes sense and is in the correct units!