Ideal Gas Assumption laws + kinetic molecular theory

Kinetic Molecular Theory + Ideal Gas assumptions

What is an ideal gas?

• What does that mean for temperature,

• what does that mean for pressure

An ideal gas will be perfectly predicted by the ideal gas law.

Most gasses act like an ideal gas.

• Ideally at high temperature and low pressure

Ideal Gas assumptions (5)

ASSUMPTIONS

• Gas particles volumes are insignificant compared to the massive space between them

• Gas particles experience ZERO intermolecular forces with each other and their containers.

• Gas particles are always in continuous, random motion.

• Gas molecules collisions with each other are perfectly elastic, so there is zero loss of kinetic energy when they collide.

• The average kinetic energy of a gas depends only on the systems temperature.

The one bolded is most accurate at low temperatures.

The one italicized is most accurate at high temperatures.

Boyle’s Law

Decreasing the volume of something, the pressure increases.

V = 1/P

Charles’ Law

As long as everything remains constant, volume is proportional to temperature.

Avogadro’s Law

As long as everything else remains constant, Volume is directly proportional to the number of gas moles.

MORE VOLUME = MORE MOLES

Combined Gas Law

P1V1 / n1t1 = P2 V2 / n2 t2

Ideal Gas Law

PV = nRT

R = Ideal Gas Constant

Density

Mass / Volume

gas Density

Density = P molar mass / R * T

Dalton’s Law of Partial Pressure

Total Pressure inside a container filled with multiple gases = sum of all those gases individual pressures.

Ptotal = Pa + Pb + Pc …..

Graham’s Law of Effusion

When gases escape through a narrow slit, the lighter gases esacpe (effuse) more quickly while heavier gases (higher molecular weights) effuse more slowly.

He vs O2 for example, will be He.

Even though they both have the same average kinetic energy. that only relies on temperature. So the molecules have to be moving faster (the smaller ones)

KE = ½ mass * V²

Effusion Rate of gas 1 / Effusion rate of Gas 2 = sqrt (Molecular weight of gas 2 / molecular weight of gas 1.)