Gas Laws for Respiratory

Kinetic Theory of Gases

Constant random high speed, directly proportional to temperature

Gas Pressure

Molecules colliding with each other and the wall

Basic Assumption 1

No energy is lost during molecular collision

Basic Assumption 2

Volume of the molecules themselves are negligible

Basic Assumption 3

no forces of mutual attraction exist between these molecules

Pressure

The force exerted per unit area

Volume

The space the gas occupies

Temperature

A measure of kinetic energy

Amount

The quantity of gas measured in moles

Critical Rule for temperature

All gas laws must be converted to Kelvin

ATM at sea level

1

Torr at sea level

760

mmHg at sea level

760

cmH2O at sea level

1034

PSI at sea level

14.7

cmHg at sea level

76

Gas conversion formula

(given pressure/ Given p. at sea level) X desired p. at sea level

Avogadro’s law

1 mole of any ideal gas occupies 22.4 liters at STP

STP

standard temp and pressure

1 mole

6.02 X 10²³

Avogadro’s law formula

Density= gram molecular weight (g/mol) / 22.4 (L/mol)

Density of air

1.25 g/L

Density of Helium

0.18 g/L

Boyle’s law

The volume of a gas is inversely proportional to its pressure

Boyle’s law formula

P₁ V₁= P₂V₂

Charles’s law

The volume of a gas is directly proportional to its absolute temperature

Charles’s law formula

V₁/T_{1 =} V₂ / T₂

Gay- Lussac’s law

The pressure of a gas is directly proportional to its absolute temperature.

Gay- Lussac’s law formula

P₁/T₁= P₂/T₂

The combined gas law

All 3 previous ones combined, pressure, volume and temperature

The combined gas law formula

(P₁V₁) / T₁= (P₂V₂)/ T₂

Dalton’s law of partial pressures

The total pressure of a gas mixture is equal to the sum of the partial pressures of each individual gas in the mixture

Dalton’s law of partial pressures formula

P total = P₁ + P₂ + P₃ …

gas make up of oxygen

21%

gas make up for nitrogen

78%

Henry’s law

The higher the pressure if a gas above a liquid the more of it will dissolve into the liquid

critical temperature

the highest temperature at which a substance can exist as a liquid regardless of pressure

critical pressure

the pressure required to keep a substance in its liquid state at its critical temperature