ChemAtlas

Chapter 7 · Chapter 8

Gas laws

Gases respond to pressure, volume and temperature in ways liquids and solids do not, because the molecules are mostly empty space. Every law below is one equation with something held constant.

Always in kelvin

K = °C + 273.15

R = 0.0820573 L·atm/(mol·K)

Low pressure1 atm · 10 LcompressHigh pressure2 atm · 5 LP₁V₁ = P₂V₂1 × 10 = 2 × 5Same molecules,half the room.
Fig. 8Halve the volume and the same molecules strike the walls twice as often, so the pressure doubles. That inverse relationship is Boyle's law.
Solve for
atm
L
mol
K

0.0 °C

Standard conditions

At 0 °C and 1 atm, one mole of any ideal gas fills 22.414 L. That single number turns gas volumes into moles without touching the ideal gas law.

Pressure

1atm

Volume

22.414L

Moles

1mol

Temperature

273.15K

Working

  1. 01PV = nRT, with R = 0.0820573 L·atm/(mol·K) and temperature in kelvin
  2. 02V = nRT ÷ P = (1 × 0.0820573 × 273.15) ÷ 122.414 L