Write the chemical formula of the molecule
Find the atomic mass of each element in the formula
Multiply each atomic mass by the number of atoms of that element
Add all the results to get the molecular mass in atomic mass units
Convert molecular mass to mass in grams using Avogadro’s number if needed
Use the formula: mass of one molecule = molar mass ÷ Avogadro’s number
Use the formula: mass of n molecules = n × mass of one molecule
Keep units consistent throughout the calculation