Monday, February 1, 2010

Chapter 10 Section 1

The Kinetic-Molecular Theory of Matter

• The Kinetic-Molecular Theory is based on the idea that particles of matter are always in motion
• The theory can be used to explain the properties of solids, liquids, and gases in terms of particles and the forces that act between them

The Kinetic-Molecular Theory of Gas

• An ideal gas is a hypothetical gas that perfectly fits all the assumptions of the kinetic-molecular theory
• The kinetic-molecular theory of gases is based on the following five assumptions:

1. Gases consists of large number's of tiny particles that are far apart relative to their size

• Most of the volume occupied by a gas is empty space

2. Collisions between gas particles and between particles and conatiner walls are elastic collisions

• An elastic collision is one inwhich there is no net loss of total kinetic energy

3. Gas particles are in continuous, rapid, random motion. They therefore possess kinetic energy which is energy of motion

4. There are no forces of attraction between gas particles

5. The temperature of a gas depends on the average kinetic energy of the particles of the gas

• The kinetic energy of any moving object is given by this equation: KE= (1/2)(m)(v)^2
• V- velocity M-kilograms K-Kinetic Energy Answer is in Joules(J)

The Kinetic Molecular Theory of Gas(continued)

• All gases at the same temperature have the same average kinetic energy
• At the same temperature, lighter gas particles, have higher average speeds than do heavier gas particles
• Hydrogen molecules will have a higher speed than oxygen molecules

The Kinetic-Molecular Theory and the Nature of Gases

• The Kinetic-Molecular Theory applies only to ideal gases
• Many gases behave nearly ideally if pressure isn't very high and temperature isn't very low

Expansion

• Gases don't have a definite shape or a definite volume
• The completely fill any container in which they are encolsed
• Gas particles move rapidly in all directions (assumption 3) without significant attractino between them (asumption 4)

Fluidity

• Because the attraction forces betwen gas particles are insignificant (assumption 4) gas particles glide easily past one another
• Because liquids and gases flow, theyre both referred to as fluids

Low Density

• THe density of a gaseous substance at atmosphere pressure is about 1/1000 the density of the same substance in the liquid or solid state
• The reason is that the particles are so much farther apart in the gaseous state (assumption 1)

Compressibility

• During compression, the gas particles, which are initially very far apart (assumption 1) are crowded close together

Diffusion and Effusion

• Gases spread out and mix with one another, even without being stirred
• The random and continuous motion of the gas molecules (assumption 3) carries them throughout the available space
• Such spontaneous mixing of the particles of two substances by their motion is called diffusion
• Effusion is a process by which gas particles pass through a tiny opening
• The rates of effusion of different gases are directly proportionally to the velocities of their particles
• Molecules of low mass effuse faster than molecules of high mass

Deviations of Real Gases from Ideal Behavior

• Because particles of gases occupy space and next attractive forces on each other, all real gases deviate to some degree from ideal gas behavior
• A real gas is a gas that doesn't behave completely according to the assumptions of the kinetic-molecular theory
• At very high pressures and low tempreratures a gas is most likely to behave like a non-ideal gas
• The more polar the molecules if a gas are, the more the gas will deviate from ideal gas behavior

Chapter 10 Section 2

Liquids

Properties of Liquids Kinetic-Molecular Theory

• A liquid can be descried as a form of matter that has a definite volume and takes the shape of its container
• The atractive forces between particels in a liquid are more efective than those between particles in a gas
• This attraction between liquid particles is caused by the intermolecular forces
• Dipole-Dipole forces
• London dispersion forces
• Hydrogen Bonding