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Ideal gases and the ideal gas law; - Coggle Diagram

- - - - There are no (or entirely negligible) intermolecular forces between the gas molecules.
      - The volume occupied by the molecules themselves is entirely negligible relative to the volume of the container.
- - - - 1 atmosphere = 101325 Pa
        1 bar = 100 kPa = 100000 Pa.
    - - Note; You may come across other values for this with different units. A commonly used one in the past was 82.053cm^3atmK^-1mol^-1. The units tell you that the volume would be in cubic centimetres and the pressure in atmospheres. Unfortunately the units in the SI version aren't so obviously helpful.
- - - - Now if you add up the relative formula mass of ethane, C2H6 using accurate values of relative atomic masses, you get an answer of 30.07 to 4 sigfigs. Which is different from our answer (30.4), so whats wrong?;
        
        The density value I used may not be correct. I did the sum again using a slightly different value quoted at a different temperature from another source. This time I got an answer of 30.3. So the density values may not be entirely accurate, but they are both giving much the same sort of answer.
        
        Ethane isn't an ideal gas. Well of course it isn't an ideal gas - there's no such thing! However, assuming that the density values are close to correct, the error is within 1% of what you would expect. So although ethane isn't exactly behaving like an ideal gas, it isn't far off.