Ideal Gases
Physics: AQA A Level, topic 6.2.3
The Kelvin Scale
The Kelvin scale is a temperature scale that is commonly used in science.
The Kelvin scale
- The Kelvin scale is an absolute temperature scale defined to have 0 K at the lowest possible temperature, called absolute zero.
Absolute zero
- Absolute zero (0 K) is the lowest possible temperature.
- At absolute zero, there is no temperature.
- This means that there is no kinetic energy or vibration of molecules.
Converting from degrees Celsius to Kelvin
- To find degrees Celsius from Kelvin, just add 273.15.
- E.g. 0oC = 273.15 K.
- E.g. Water boils at 373.15 K.
Ideal Gas Law
The ideal gas law is a good model for the behaviours of large amounts of gas.
Ideal gas law
- The ideal gas law can be written as:
- Pressure x volume = number of moles x ideal gas constant x temperature
- pV=nRT
- Where R is the ideal gas constant and has a value of 8.31
- This equation can be rearranged to solve for any of the terms.
Boltzmann constant
- Ideal gas constant x number of moles = Boltzmann constant x number of molecules
Avogadro's number
- This equation gives the relationship between the ideal gas constant, the Boltzmann constant and Avogadro's number (the number of molecules in a mole):
- Using the ideal gas law and the above equation, we can now write:
Test yourself on Ideal Gases
How do particles move at absolute zero?
Which statements about absolute zero are correct?
Which form of the ideal gas law is correct?
What is the correct equation for the Boltzmann constant?