Gas pressure
If the The volume of a three-dimensional shape is a measure of the amount of space or capacity it occupies, eg an average can of fizzy drink has a volume of 330 ml. of a container with a gas inside stays the same, the pressure of a gas increases as its A measure of the average kinetic energy of particles in a substance. increases.
When hotter, the gas particles will be travelling faster and will collide with the walls of the container more frequently and with more A push or a pull. The unit of force is the newton (N)..
This means that there is a relationship between
Kelvin temperatures
As the temperature of a gas increases, the pressure increases, showing a linear relationship between the two. If the temperature axis is rescaled, the graph shows that pressure is directly When two quantities have the same ratio or relative size. For example, current is proportional to voltage if the current doubles when the voltage is doubled. to temperature.
The rescaling needed is to put the zero on the temperature scale at -273 °C. This is an alternative temperature scale called the Kelvin (or 'absolute') scale of temperature. This new zero of temperature is called A temperature where the kinetic energy of a particle is zero, eg absolute zero has a temperature of 0 K.. At absolute zero, the average kinetic energy of the particles is zero and they stop moving.
Each degree Celsius is the same size as one kelvin. Raising the temperature by one degree Celsius also increases the value on the kelvin temperature scale by one.
| Temperature | Celsius scale | Kelvin scale |
| Boiling water | 100°°ä | 373 K |
| Freezing water | 0°°ä | 273 K |
| Absolute zero | -273°°ä | 0 K |
| Typical room temperature | 20°°ä | 293 K |
| Temperature | Boiling water |
|---|---|
| Celsius scale | 100°°ä |
| Kelvin scale | 373 K |
| Temperature | Freezing water |
|---|---|
| Celsius scale | 0°°ä |
| Kelvin scale | 273 K |
| Temperature | Absolute zero |
|---|---|
| Celsius scale | -273°°ä |
| Kelvin scale | 0 K |
| Temperature | Typical room temperature |
|---|---|
| Celsius scale | 20°°ä |
| Kelvin scale | 293 K |
- To convert °C into K, add 273.
- To convert K into °C, subtract 273.