Cracking the AP Chemistry Exam

Part IV

Content Review for the AP Chemistry Exam

Chapter 4

Big Idea #2: Bonding and Phases

Chemical and physical properties of materials can be explained by the structure and the arrangement of atoms, ions, or molecules and the forces between them.

KINETIC MOLECULAR THEORY

For ideal gases, the following assumptions can be made:

· The kinetic energy of an ideal gas is directly proportional to its absolute temperature: The greater the temperature, the greater the average kinetic energy of the gas molecules.

The Average Kinetic Energy of a Single Gas Molecule

KE = mv²

m = mass of the molecule (kg)

v = speed of the molecule (meters/sec)

KE is measured in joules

· If several different gases are present in a sample at a given temperature, all the gases will have the same average kinetic energy. That is, the average kinetic energy of a gas depends only on the absolute temperature, not on the identity of the gas.

· The volume of an ideal gas particle is insignificant when compared with the volume in which the gas is contained.

· There are no forces of attraction between the gas molecules in an ideal gas.

· Gas molecules are in constant motion, colliding with one another and with the walls of their container without losing any energy.