Use the formula: moles = mass ÷ molar mass
Measure the mass of the substance in grams
Find the molar mass from the periodic table or chemical formula
Divide the mass by the molar mass
Use the formula: moles = number of particles ÷ Avogadro’s number
Use Avogadro’s number = 6.022 × 10^23 particles per mole
Use the formula: moles = volume ÷ molar volume for gases at STP
Use molar volume = 22.4 L per mole at STP
Use the formula: moles = concentration × volume for solutions
Measure concentration in mol/L and volume in liters