Ideal gases are simply a hypothetical "perfect" gas. They obey all three laws; Boyle's law, Charle's law and Avogadro's law. According to the Kinetic Particle theory of gasses, an ideal gas will have:
-negligible gas particle size as compared to the size of the container
-negligible intermolecular forces
-gas particles that are in constant random motion
-gas particles that participate in perfectly elastic collisions
However, in reality, there is no known gas that have obeyed all of the properties mentioned above. So far, scientists have tried to achieve ideal gas state but only got close. Even the smallest molecule, Hydrogen, deviates from ideal gas behavior.
Since ideal gasses are hypothetical, and no such gas exist, we only study how far a gas deviates from ideal gas behavior. Deviation can be compared by comparing the differences in the properties mentioned above between different gases. E.g. CO2 larger size than H2, hence deviates more.
We can predict properties of gases by using the ideal gas equation: pV=nRT where
p-pressure in Pa
V-volume in m^3
n-amount in mol
R-universal gas constant (8.314)
T-temperature in K
The values obtained from the equation deviates from the empirical value as we assume the gas to be ideal (which its not). Therefore we can only predict.
