What a mole actually is

3 mistakes we see every year

• Using mass number instead of molar massRead the molar mass off the periodic table, in g/mol.molar mass
• Multiplying mass by molar massMoles = mass ÷ molar mass. Check the units cancel.divide
• Counting H2O as one H and one OMultiply each atomic mass by its subscript, then add.subscript