3.4a The concept of an ideal gas is a model to explain the behavior of gases. A real gas

is most like an ideal gas when the real gas is at low pressure and high temperature.

3.4b Kinetic molecular theory (KMT) for an ideal gas states that all gas particles:

• are in random, constant, straight-line motion.

• are separated by great distances relative to their size; the volume of the gas

particles is considered negligible.

• have no attractive forces between them.

• have collisions that may result in a transfer of energy between gas particles, but

the total energy of the system remains constant.

3.4c Kinetic molecular theory describes the relationships of pressure, volume, tempera-ture,

velocity, and frequency and force of collisions among gas modules.

3.4d Collision theory states that a reaction is most likely to occur if reactant particles

collide with the proper energy and orientation.

3.4e Equal volumes of gases at the same temperature and pressure contain an equal

number of particles.

3.4f The rate of a chemical reaction depends on several factors: temperature, concentra-tion,

nature of the reactants, surface area, and the presence of a catalyst.

3.4g A catalyst provides an alternate reaction pathway, which has a lower activation

energy than an uncatalyzed reaction.

3.4h Some chemical and physical changes can reach equilibrium.

3.4i At equilibrium the rate of the forward reaction equals the rate of the reverse

reaction. The measurable quantities of reactants and products remain constant at


3.4j LeChatelier's principle can be used to predict the effect of stress (change in pres-sure,

volume, concentration, and temperature) on a system at equilibrium.