1. Behavior of Gases

2. Gas particles are in constant motion Collisions of these particles in the air causes pressure Pressure = force per unit of area or P = F/A

3. The more gas particles in a container the more they collide with the walls of the container and the greater the pressure

4. Pressure is measured in a unit called a Pascal (Pa) P = F/A; F measured in Newtons (N) and A measured in m 2 Pascal = N/m 2 Since 1 N/m 2 is such a small unit we typically record pressure in kPa or kilopascals

5. Boyle’s Law If you increase the volume of a container of gas, and hold the Temp constant, Pressure will be decreased – Volume – Pressure If you decrease the volume of the container and hold the temperature constant, Pressure will increase – Volume – Pressure

6. Boyle’s Law in Action Since pressure and volume are INDIRECTLY related the following equation can be formed: – P 1 V 1 = P 2 V 2 – Using this equation you can find missing values – Assumes constant temperature

7. Example of Boyle’s Law If a balloon has a volume of 10 L at a pressure of 101k Pa. What will be the new volume when the pressure drops to 43.0 kPa?

8. Pressure/ Temp Relationship If you heat gas particles they move faster The faster they move the more they strike the sides of their container If the container is a FIXED volume (can’t expand), the pressure will increase as the Temp increases Temp Pressure ***Constant Volume

9. If Temperature is increased then one of the other factors must also increase due to faster moving particles: – With a fixed volume then the pressure will increase – With a fixed pressure then the volume will Increase (balloons)

10. Charles’ Law In some cases where the container can expand, the volume increases not the pressure: Volume of gas increases as temp increases as long as pressure does NOT change – Volume – Temperature – **The reverse is also true: volume decreases as temperature decreases

11. Charles’Law The following equation depicts Charles’ Law V 1 / T 1 = V 2 / T 2 – Temp is in Kelvin – Pressure is constant

12. Example of Charles’ Law What would be the resulting volume if a 2.0 L balloon at 25° C that was placed in a container of ice water at 3°C? – To convert celsius to Kelvin simple add 273 and drop the degrees symbol