# Amount of Substance: Equations and Calculations

## Amount of Substance: Equations and Calculations

- Number of particles can be calculated by the formula: number of particles = moles x Avogadro’s constant
- Moles of a substance can be calculated by dividing the mass by the molar mass (Mr): moles (mol) = mass (g) /Mr (g/mol)
- Concentration can be calculated by dividing the amount of substance by volume: concentration (mols/dm³) = amount of substance (mols) / volume (dm³)
- The ideal gas law equation is: pV = nRT