Gas Laws Formulas

Boyle’s Law

Boyle’s Law

P₁V₁ = P₂V₂

Charles’s Law

V₁/T₁ = V₂/T₂

Gay-Lussac’s Law

P₁/T₁ = P₂/T₂

The Combined Gas Law

P₁V₁/T₁ = P₂V₂/T₂

Daltons Law

Ptotal = P₁ + P₂ + P₃ + …

Mole fraction

PA = X_A*P_total where X_A= mol_A/mol_total

Ideal Gas Law

PV = nRT

Ideal Gas Law: when P is atm, R is

0.08206

Ideal Gas Law: when P is kPa, R is

8.314

Ideal Gas Law: when P is mmHg, R is

62.4

(Use when asked to solve problems involving density of a gas or to identify it based on calculation of its molar mass)

PV = nRT where n = mass/MM

PV = (mass/MM) RT

(Use when asked to solve problems involving density of a gas or to identify it based on calculation of its molar mass)

MM = (mass*RT)/PV where D = mass / V

MM = (DRT) / P

STP

Standard Temperature and Pressure

Standard Pressure

1 atm = 760 torr = 760 mmHg = 101.3 kPa

Standard Temperature

0^oC = 273 K

Boyle’s Law : Inverse or Direct

Inverse

Charles’s Law: Inverse or Direct

Direct

When to use Boyle’s Law?

For a given mass at constant temperature

When to use Charles’s Law

Pressure is constant

When to use Gay-Lussac’s Law

When volume is constant

Gay-Lussac’s Law: Inverse or Direct

Direct

When to use the Combined Gas Law?

Amount of gas is constant