01PV = nRT
Pressure, volume, moles and temperature are linked: PV = nRT. Temperature must be in kelvin. R = 0.08206 L·atm/(mol·K).
Partial pressures add (Dalton): P_total = ΣP_i, and P_A = X_A · P_total.
02Notebook box
Combined: P₁V₁/T₁ = P₂V₂/T₂. Molar mass: M = dRT/P.
Worked example: 2.0 mol gas at 300 K in 10 L → P = (2)(0.0821)(300)/10 = 4.9 atm.