Unit 3: Topic 6 - Deviation from Ideal Gas Law Flashcards
Where do significant deviations to the ideal gas law begin to occur? (Where does the ideal gas law no longer become a good approximation?)
Significant deviations to the ideal gas law occur at low temperatures or high pressures.
Explain the deviations from the ideal gas law and its relationship with the van der Waals equation.
The van der Waals equation is given by (P + an^2/V^2)(V - nb) = nRT. P, V, n, R, and T are still pressure, volume, moles, ideal gas constant, and temperature, while a and b are correction terms to the ideal gas equation. The deviations in the new van der Waals equation account for deviations at high pressure: there is a force of attraction between gases (otherwise, they could not condense to liquid). The correction term for pressure is proportional to a gas constant “a”, unique for each gas. Similarly, at this super high pressure, the gaseous particles actually make up a sizable fraction of the container. Thus, there should be a term proportional to the moles of gas subtracted from the volume: V - nb, with b the constant depending on the gas. (Article provided, it is much more in-depth than that required on AP Chemistry)
