Journal Entry 10

Final touches to Kinetic Particle Theory

Kinetic Particle Theory is a model, the best representative symbol of what really happens in those teeny weeny things.

A scientific model is
- a representation, prototype or replica of the object/phenomenon that could well explain its physical properties
- phenomenon include physical phenomenon like diffusion, dissolving, boiling, condensation, evaporation, melting, sublimation etc
- physical properties include volume, density and conductivity etc

Assumption are valid statements to set the parameters for the model to work. Without the assumptions, the principles of the model become invalid or irrelevant.

Limitations are features of the model not aligned with the actual properties and go against the principles of the phenomenon.

Assumptions of the Kinetic Particle Theory:
- Particles are in constant and random motion.
- Particle possess kinetic energy.
- Forces of attraction exist between particles.
- Heavier particles travel slower than lighter particles.
- Particles do not stick to each other.
- Particles do not stick with the walls of the container and bounces back after collision with the walls of container.
- Particles travel in a straight line.
- Particles are small and discrete.

Limitations of the Kinetic Particle Theory:
- Forces of attraction between particles are not seen in the model.
- Size of the particles of an element may not be uniform,
- Distance between particles in model may not be accurate.
- Size of the particles in model may not be scaled accurately to the actual particles' size.


THE END

Chemistry Journal Entry 8

For the past 2 weeks, we learnt more about the Kinetic Particle Theory.

Basically, all particles are in constant motion and thus, they have kinetic energy. Gases have the highest energy content, followed by liquids and the state with the least energy content, solid.

MELTING

When a substance changes from a solid to a liquid, it is melting.

- Describe the properties of a solid first.
- Heat energy is absorbed by the particles in the solid.
- The heat energy is converted into kinetic energy.
- The particles start to vibrate faster about their fixed positions.
- When the temperature is high enough, the vibrations of the particles become sufficient to overcome the attractive forces between them.
- The particles begin to break away from their fixed positions.
- The particles are no longer in their fixed positions.
- The particles slide over one another.
- Now becomes a liquid.
- Describe the properties of a liquid.

* When looking at a graph of temperature against time, we can deduce certain things. Let us look at the graph below.

We call this a heating curve. From points 1 to 2, the solid heats up. At point 2 to 3, the solid melts. At point 4, the liquid is heating up. 

FREEZING 

When a substance changes from a liquid to solid, it is freezing. 

-Describe the state of the liquid. 

- Heat energy is absorbed by the particles in the solid. 

- The heat energy is converted to kinetic energy.

- The particles start to vibrate faster about their fixed positions. 

- When the temperature is high enough, the vibrations of the particles become sufficient enough to overcome the attractive forces between them. 

- The particles begin to break away form their fixed positions. 

- The particles are no longer in their fixed positions.

- The particles slide over one another.

- Becomes a liquid

- Describe the state of liquid. 

BOILING 

When a substance changes from a liquid to a gas, it is called boiling. 

- Energy is absorbed by particles in the liquid. 

- Particles gain kinetic energy and start to move faster as the temperature rises. 

- Eventually, the particles throughout the liquid have enough energy to overcome the forces holding them together.

- The particles can now spread far apart and move rapidly in all directions.

- Now a gas. 

EVAPORATION 

* Liquids that evaporate quickly at room temperature is called volatile liquids. 

* Evaporation and boiling are 2 different processes.

There are 3 differences:

1) Boiling occurs only at boiling point while evaporation occurs at temperatures below boiling points.

2) Boiling occurs throughout the liquid while evaporation occurs only at the surface of the liquid. 

3) Boiling occurs rapidly while evaporation occurs slowly. 

CONDENSATION 

When a gas is cooled sufficiently, it changes into a liquid. 

When water vapor touches a cold surface, condensation occurs and liquid water is obtained. 

-Heat energy is given out during condensation. 

-As the temperature drops, the gas particles lose energy and move more slowly.

- The movement of the particles become slow enough for the gas to change into a liquid. 

SUBLIMATION

Solid changes into gas directly without going through the liquid state -> Sublimation

Gases that can sublime : Iodine

 Opposite of sublimation: Deposition

The KPT is a model and hence, it has many assumptions and limitations. More will be explained in my next journal entry!

Thank you!