1. Introduction to Gas Laws Chapter 14 Benchmark 4

2. Pressure The force per unit area that the particles in the gas exert on the walls of their container.

3. Pressure = 1 pascal (Pa) Examples of pressure: –Atmospheric pressure = 10 5 Pa –Helium tank = 10 7 Pa –Hydrogen in outer space = 10 -23 Pa –Vacuum = 0 Pa Because of pressure, volume can be compressed. A helium tank with 44L can fill 6500 L of balloons.

4. According to the kinetic theory, all matter is composed of particles in constant motion, and pressure is caused by the force of gas particles striking the walls of their container. The more often gas particles collide with the walls of their container, the greater the pressure. Collisions = Pressure!!

5. Measuring Pressure Barometer mercury Atmospheric pressure

6. STP Standard Temperature and Pressure Temperature = 0°C Pressure = 101325 Pa (pascals) 101.325 kPa (kilopascals) 1.00 atm (atmospheres) 760 mmHg (millimeters mercury) 760 torr 14.7 psi (pounds per square inch) (used in the US)

7. Conversions Ex 1: 75.0 kPa = ? atm 75.0 kPax 1.00 atm 101.325 kPa =0.740 atm Ex 2: 2315.1 Pa = ? Torr 2315.1 Pa x760 torr 101325 Pa = 17.365 Torr