Chapter 2: Kinetic Particle Theory

What is the kinetic particle theory?

The kinetic particle theory states that all matter is made up of tiny particles and these particles are in constant random motion.

Describe a solid in terms of kinetic particle theory.

1. Very closely packed in an orderly manner
2. Very strong attractive forces
3. Vibrate about their fixed positions

Describe a liquid in terms of kinetic particle theory.

1. Closely packed in a disorderly manner
2. Strong attractive forces
3. Slide past one another freely

Describe a gas in terms of kinetic particle theory.

1. Far apart in a disorderly manner
2. Weak attractive forces
3. Move quickly and randomly in any direction

What is the term for freezing, melting and boiling points?

Transition temperatures

Describe the process of melting (converting between solid and liquid)

1. As the solid is heated, thermal energy is converted to kinetic energy in the particles,
2. causing the particles to vibrate faster aboout thier fixed positions.
3. Its temperature rises until it reaches its melting point.
4. When it has reached its melting point, all of the thermal energy is converted to kinetic energy in the particles to overcome the forces of attraction in solid state
5. The orderly packed arrangement of the particles is disrupted.
6. The temperature remains constant until all the solid has melted.
7. After all the solid has melted, the temperature will rise beyond its melting point
8. Thermal energy is converted to kinetic energy in the particles again
9. The particles can now freely slide past one another in the liquid.

Describe the process of freezing (converting between liquid and solid)

1. As the liquid is cooled, kinetic energy in the particles is converted to thermal energy which is transferred to the surroundings,
2. causing the particles to slow down
3. Its temperature decreases until it reaches its freezing point.
4. When it has reached its freezing point, the particles with less energy are drawn closer together by the forces of attraction between them.
5. The arrangement of the particles becomes more orderly
6. The temperature remains constant until all the liquid has completed freezing
7. After all the liquid has froze, the temperature will lower beyond its freezing point
8. Kinetic energy in the particles is converted into thermal energy in the surroundings again
9. The particles now instead vibrate about their fixed positions

Explain how an object undergoes expansion with kinetic particle theory.

When an object is heated, thermal energy is transferred from the surroundings to the particles which is converted to kintetic energy. The particles possess more kinetic energy, so they vibrate faster and move about more than before. The solid has undergone expansion.

Explain how an object undergoes contraction with kinetic particle theory.

When an object is cooled, thermal energy is transferred from the particles to the surroundings. The particles possess less kinetic energy, so they vibrate slower and come closer than before. The solid has undergone contraction.

Describe the process of boiling(converting between liquid and gas)

1. As the liquid is heated, thermal energy is converted to kinetic energy in the particles,
2. causing the particles to slide past one another with increasing speed
3. Its temperature rises until it reaches its boiling point.
4. When it has reached its boiling point, all of the thermal energy absorbed from the surroundings is converted to kinetic energy in the particles to overcome the forces of attraction in liquid state
5. The particles move further apart, quickly and randomly
6. The temperature remains constant until all the liquid has boiled off.
7. After all the liquid has boiled off, the temperature will rise beyond its boiling point
8. Thermal energy is converted to kinetic energy in the particles again
9. The temperature of the gas rises beyond the boiling point

Describe the process of condensation (converting between liquid and gas)

1. As the liquid is cooled, kinetic energy in the particles is converted to thermal energy which is transferred to the surroundings,
2. causing the particles to slow down
3. Its temperature decreases until it reaches its condensation point.
4. When it has reached its freezing point, the particles with less energy are drawn closer together by the forces of attraction between them.
5. The arrangement of the particles becomes less disorderly
6. The temperature remains constant until all the liquid has condensed
7. After all the gas has condensed the temperature will lower beyond its freezing point
8. Kinetic energy in the particles is converted into thermal energy in the surroundings again
9. The particles now instead slide past each other freely throughout the liquid only.

What is diffusion?

Diffusion is the net movement of particles from a region of higher concentration to a region of lower concentration

What are some conditions that affect the rate of diffusion?

Temperature and particle mass

Explain how temperature affects rate of diffusion.

As the temperature of a substances increases, the rate of diffusion also increases due to the greater average kinetic energy possessed by the particles

Explain how particle mass affects rate of diffusion.

As the particle mass of a particle increases, the kinetic energy required to move at a given speed increases and hence the time taken to diffuse also increases.