Chapter 10 Gases James F. Kirby Quinnipiac University Hamden, CT Lecture Presentation ? 2015 Pearson Education, Inc. 1 Characteristics of Gases Physical properties of gases are all similar. Composed mainly of nonmetallic elements with simple formulas and low molar masses. Unlike liquids and solids, gases expand to fill their containers. are highly compressible. have extremely low densities. Two or more gases form a homogeneous mixture. Gases ? 2015 Pearson Education, Inc. 2 Properties Which Define the State of a Gas Sample Temperature Pressure Volume Amount of gas, usually expressed as number of moles Having already discussed three of these, we need to define pressure. Gases ? 2015 Pearson Education, Inc. Pressure is the amount of force applied to an area: Pressure