Chemistry formulae

Amount of a substance

amount (mol) = mass of substance (g) / molar mass (g mol^-1)

n = \frac{m}{M}

Mass of a substance

mass (g) = amount of substance (mol) × molar mass (g mol^-1)

m = n \times M 

Molar mass of a substance

molar mass (g mol^-1) = mass of substance (g) / amount of substance (mol)

M = \frac{m}{n} 

Avogadro constant

6.02 × 10²³ mol^-1

Percentage yield

Percentage yield (%) = (actual yield × 100%) / theoretical yield

Atom economy

Atom economy (%) = (molar mass of desired product × 100%) / sum of molar masses of all products

Ideal gas equation

pV = nRT

p = pressure (Pa)

V = volume (m³)

n = amount of substance (mol)

R = the gas constant (8.31 J mol^-1 K^-1)

T = temperature (K)

kPa → Pa

× 10³

cm³ → m³

× 10^-6

dm³ → m³

× 10^-3

°C → K

+ 273

Molar volume

molar volume = 24.0 = volume (dm³) / amount (mol)

V_m = 24.0 = \frac{V \mathrm{dm^3}}{n} 

molar volume = 24 000 = volume (cm³) / amount (mol)

V_m = 24 000 = \frac{V \mathrm{cm^3}}{n} 

Mass concentration

mass concentration (g dm^-3) = mass of solute (g) / volume of solution (dm³)

mass concentration = \frac{m}{V} 

(Molar) concentration

concentration (mol dm^-3) = amount (mol) / volume (dm³)

c = \frac{n}{V}

Concentration in ppm

concentration (ppm) = (mass of solute × 1 000 000) / mass of solvent

concentration (ppm) = (volume of gas × 1 000 000) / volume of air

Ionisation energy

Ionisation energy (IE) = energy of electron when removed - energy of electron when in the orbital