= force per unit area that a gas exerts on a surface. Measured in Pascals.
I Pa = 1 Nm-2
Dependent on the temperature, volume of gas container and mass of gas.
The gas pressure x it's volume is constant providing the mass and temperature remains the same.
A change at constant temperature = isothermal change.
If you plot a graph of pressure against 1/volume, you get a straight line as pV= constant equals p = constant x 1/V.
pV = constant
- Plotting the measurements of the volume of a gas at 0 and 100 degrees Celsius, shows absolute zero is -273.15 degrees whatever volume used.
- This graph is a straight line passing through the axis at (absolute) zero, therefore:
V/T = constant
The pressure law
- The pressure of a fixed mass and volume of gas is measured when temperature is increased.
- The measurements are plotted an they give a straight line through the origin therefore:
P/T = constant