GENCHEM - Gas Laws

gases

not having a definite shape and volume

pressure

force exerted per area

air pressure

force exerted on the walls of container in collision

barometer

measures atmospheric pressure

Evangelista Torricelli (1643)

Italian who invented barometer

manometer/pressure guage

measures pressure in a closed system

• atm

• torr

• mm Hg

• Pa

• psi

units of measure for pressure:

• 1 atm

• 760 torr

• 760 mm Hg

• 101 325 Pa

• 14.7 psi

pressure in sea level at different units:

kinetic molecular theory

describes the nature of gases and the behavior of the particles that comprise them

• gas consists of minute particles

• gas particles are constantly moving and collide with each other

• gas particles are hard spheres such that their collisions are perfectly elastic (no energy is lost during collision)

• interaction among particles are negligible

• average kinetic energy of a gas is directly proportional to its absolute temperature expressed in Kelvin

KMT postulates

Boyle’s law

states that the pressure of a fixed amount of gas is inversely proportional to its volume at constant temperature

Robert Boyle

studied pressure and volume relationship of a confined gas at constant temp

P₁V₁ = P₂V₂

Boyle’s Law Formula:

Gay-Lussac’s Law

states the pressure of a fixed amount of gas is directly proportional to its absolute temperature at a constant volume

Joseph-Louis Gay-Lussac

discovered that all gases expand equally over a temperature range

P₁/T₁ = P₂/T₂

Gay-Lussac’s Law Formula:

Charles’ Law

states that the volume of a gas is directly proportioatal to its absolute temperature at a constant pressure

Jacques Charles

discovered volume-temperature relationship at constant pressure

V₁/T₁ = V₂/T₂

Charles’ Law Formula:

Ideal Gas Equation

links all three variables to the amount of a gas expressed in mole

ideal gas

theoretical gas which satisfies the assumptions of KMT

V = nRT/P

ideal gas equation:

R = 0.0821 atmL/molK

value of R in ideal gas equation:

Combined Gas Law

Boyle, Charles, and Gay-Lussac’s Law combined into a single equation

P₁V₁/T₁ = P₂V₂/T₂

Combined Gas Law equation: