The Gas Laws Section 3.2

 What happens to your lungs when you take a deep breath?

Pressure I. Pressure – The result of a force distributed over an area A. SI Unit = Pascal (Pa) *1 Pascal = Newton/meter 2 1. A Newton is a measure of force 2. (Meter) 2 is a measure of area Pa = 1 kPa

Pressure B. The pressure in a closed container of gas is caused by collisions between the particles of a gas and the walls of the container 1. The speed and frequency of collision have a direct affect on pressure 2. As speed increases the pressure increases, as speed decreases the pressure decreases 3. The mass of the particles also affects the pressure

Factors that Affect Gas Pressure A. Temperature 1. Raising the temperature of a gas will increase the pressure if the volume of the gas and number of particles are constant 2. As the temperature rises, the average kinetic energy of the particles in the air increases 3. With increased kinetic energy, the particles move faster and collide more often with the walls of the container

B. Volume 1. Reducing the volume of a gas increases its pressure if the temperature of the gas and the number of particles are constant 2. As the volume is decreased, particles of trapped air collide more often with the walls of the container

C. Number of Particles 1. Increasing the number of particles will increase the pressure of a gas if the temperature and the volume are constant 2. The more particles there are in the same volume, the greater the number of collisions and the greater the pressure

Charles’s Law A. States that the volume of a gas is directly proportional to its temperature in Kelvin if the pressure and the number of particles are constant B. Absolute zero – the temperature of 0 K or -273°C

C. The formula equals 1. Temperature must be written in Kelvin (add 273 to temperature in written in Kelvin (add 273 to temperature in Celsius to get Kelvin) Celsius to get Kelvin) D. As a gas cools to temperatures near 0K, the gas changes to a solid, liquid, or sometimes a Bose-Einstein condensate

Charles’s Law

Boyle’s Law A. The volume of a gas is inversely proportional to its pressure if the temperature and the number of particles are constant. B. The formula equals P 1 V 1 = P 2 V 2

Boyle’s Law

The Combined Gas Law A. Describes the relationship among the temperature, volume, and pressure of a gas when the number of particles is constant B. The formula equals C. Scientists need laws to deal with situations in to deal with situations in which multiple variables which multiple variables are changing are changing V2V2

D. What will happen to the volume of a weather balloon as it rises through the atmosphere? 1. A decrease in pressure should cause the balloon to expand to a larger volume 2. A decrease in temperature should cause the balloon to contract to a smaller volume 3. Whether the balloon expands or contracts depends on the size of the changes in pressure and temperature

Plot Boyle’s Law

Plot Charles’s Law