| Understandings |
|---|
| Molecular theory of solids, liquids and gases |
| Temperature and absolute temperature |
| Internal energy |
| Specific heat capacity |
| Phase change |
| Specific latent heat |
| Applications and Skills |
|---|
| Describing temperature change in terms of internal energy |
| Using Kelvin and Celsius temperature scales and converting between them |
| Applying the calorimetric techniques of specific heat capacity or specific latent heat experimentally |
| Describing phase change in terms of molecular behaviour |
| Sketching and interpreting phase change graphs |
| Calculating energy changes involving specific heat capacity and specific latent heat of fusion and vaporization |
$$ Q = mc\Delta t \\Q = mL $$
Three phases of matter exist: solid, liquid and gas.
In a solid there are forces between the particles that can be modelled by springs joining neighbouring particles. The springs then represent the bonds between the particles.
In liquids the forces between the particles are weaker. The particles are able to move around the volume of the liquid and the liquid will take the shape of the container in which it is placed.
In gases the inter-particle forces are almost negligible. The only time significant forces exist between the particles is during collisions.
Temperature can be described as the “degree of hotness” of an object if we refer to our senses.
In Physics the concept of temperature is related to the random motion of molecules: temperature is proportional to the average random kinetic energy of the molecules.
There has to be an absolute zero in temperature since there is a lowest possible value of the average kinetic energy of molecules, namely zero kinetic energy.
The connection between the Celsius and Kelvin scales is:
$$ T(\text{in kelvin, K}) = T(\text{in degrees Celsius, C}\degree) +273 $$
Degree Celsius and Kelvin have the same magnitude.
Example 1