The Ideal Gas Law

T

Temperature in Kelvin

P

Pressure with a value of 1 atm (SI unit)

V

volume with the SI unit of m³

n

Amount of gas/number of moles

An ideal gas

PV = nRT

R

molar gas constant

The characteristics of an ideal gas

The volume of an ideal gas is negligible compared to the volume of its container

The particles have zero intermolecular force of attraction

Ideal Gas

Gas particles exert pressure by constant collision with the walls of their container

The SI unit of atmospheric pressure is

Pascal (Pa)

Quantity-Volume Relationship: Avogadro’s Law

Equal volumes of gases at the same temperature and pressure contain equal numbers of molecules

Quantity-Volume Relationship

V₁/n₁ = V₂/n₂

Lowest possible temperature

absolute zero

0 K is equivalent to

-273.15 ℃

Temperature-volume relationship

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

V₁/T₁ = V₂/T₂

A plot of volume against temperature gives

a straight line which intercepts the volume and temperature axis at zero

Temperature-Volume Relationship: Charles’s Law

at constant pressure

the volume of a gas sample expands when heated and contracts when cooled

volume of gas decreased as the pressure increased

the pressure increased

Pressure-Volume Relationship

V ∝ P ; PV = constant

P₁V₁ = P₂V₂

Dalton’s Law of Partial Pressure

the total pressure of a mixture of gases equals the sum of the pressures that each would exert if it were present alone

P_T = P_A + P_B + P_C

partial pressures of the gases A, B and C

X_A known as the mole fraction of gas

mole fraction of gas A

X_A

= n_A/(n_A + n_B + n_C)

Dalton

The total pressure of a mixture of gases is equal to the sum of the pressures of each of the individual gases in the container

Boyle

The volume of a fixed amount of gas varies inversely with the pressure at constant temperature.

Charles

The temperature and volume of a gas at constant pressure are directly proportional.

Avogadro

The volume of two different gases at the same temperature and pressure is the same, and each sample contains the same number of gas molecules.