SECTION 1 PROPERTIES OF GASES Chapter 12 Gases

What are the three states of matters? List 3 properties of gases. List 3 different names of gases. Identify them as elements, compounds, or mixtures.

Properties of Gases Gases have unique properties because of large distance between particles

Compared to Solids and Liquids SolidLiquid

The distance between particles of a substance is referred to as intermolecular distance

Gases are considered Fluids Fluid – any substance that can flow Fluid describes liquids and gases

Gas particles can flow because of large intermolecular distances

Gases have Low Density Remember density = mass/volume Because of large intermolecular distances, most of the volume of a gas is empty space

Gases are Highly Compressible Syringe demonstration

Gases Completely Fill a Container

The gas will continue to fill side A until there are the same amount of particles on both sides

Gas Pressure Gases are all around us Earth’s atmosphere is filled mainly with nitrogen and oxygen

Gases have Mass Because they have mass, they have weight Earth’s gravity pulls particles downwards towards its center This is often referred to as air pressure

Ears Popping When flying in an airplane or driving up a high mountain sometimes your ears “pop” This popping happens because the density of the air changes when you change altitudes Less dense air exerts less pressure. Your ears pop when the air inside your ears changes to the same pressure as the outside air

Measuring Pressure Pressure = Force/Area = Newton/Meter 2 Pascal, Pa is the standard unit for pressure 1 Pa = 1 N / m 2

Standard Temperature and Pressure When performing experiments with gases, it is very important to consider pressure and temperature Scientists have set up a standard temperature and pressure (STP) which is equal to 0 o C and 1 atm

Kinetic Molecular Theory This states that gas particles are in constant rapid, random motion. Also states that the particles of a gas are very far apart relative to their size.

Gas particles in constant motion collide with each other and with the walls of their container. Pressure exerted by a gas is a result of collisions of the molecules against the walls of the container.