Ideal Gas Law Deviations

Model
Ideal Gas Law Equation

PV

nRT
PV=nRT
(Used for ideal gas behavior).

Ideal Gas Assumptions (KMT)

Gas molecules are insignificant in volume compared to container volume; there are no intermolecular attractions between gas molecules.

Conditions for Ideal Behavior

High temperatures and low pressures.

Deviations from Ideal Gas Law

Real gases do not behave ideally when interparticle attractions or particle volumes become significant.

Conditions for Deviations

Extremely high pressures (P > 5 atm) and/or low temperatures.

Deviation at High Pressure (Particle Volume)

At high pressures, the actual volume of the gas molecules themselves is no longer negligible compared to the container volume, leading to a smaller "free space" for the molecules to move; an adjustment must be made to the IGL.

Deviation at Low Temperature/High Pressure (IMFs)

As temperature decreases or pressure increases, the particles are closer together and/or moving slower, allowing intermolecular attractive forces (IMFs) to become significant.

Effect of Attractive IMFs (Deviation)

Attractive forces cause molecules to "clump" slightly, reducing the force and frequency of their collisions with the container walls, thus decreasing the pressure of the gas compared to the ideal predict