chem gas laws

Boyle’s Law

At constant temperature, pressure and volume are inversely related

P1V1 = P2V2

Charle’s Law

At constant pressure, volume and temperature are directly related.

V1 / T1 = V2 / T2

Gay-Lussac’s Law

At constant volume, pressure and temperature are directly related.

P1 / T1 = P2 / T2

Combined Gas Law

Combination of individual gas laws, # of molecules stays constant but everything else can change.

P1V1 / T1 = P2V2 / T2

Ideal Gas Law

Use when the problem mentions moles or grams of a substance.

PV = nRT

n - # of mols

R - universal gas constant = 8.31(L*kPa)/(mol*K)

Avogadro’s Law

At constant temperature and pressure, given volumes of gas contain the same number of particles

Dalton’s Law of Partial Pressured

The total pressure inside a container is equal to the sum of the pressures due to each individual gas.

The “partial pressure” is the contribution from each gas.

Diffusion vs. Effusion

Diffusion: How quickly gases mix with each other.

• Gasses tend to move from higher concentrations into lower concentrations

Effusion: Describes the movement of gasses from an area of higher concentration into a vacuum (evacuated/empty chamber)

• Gasses with lower molar mass tend to effuse quicker than those with higher.

Ideal Gas Particles

Volume

• Have no volume

Motion

• Move constantly

Collisions

• Have no attraction, so they do not lose energy in collisions.

Real Gas Particles

Volume

• Have volume (very small)

Motion

• In straight lines until collision

Collisions

• Have attractions, so they can lose energy in collisions.

STP

K = 273

Pressure = 100 kPa

At STP, 1 gas mol = 22.7 dm3