Final answer:
When converting between numbers of representative particles, masses, and volumes, you must always convert to moles as an intermediate step.
Step-by-step explanation:
When converting between numbers of representative particles, masses, and volumes, you must always convert to moles as an intermediate step. To convert from number of particles to moles, you use mol/Avogadro's #, and to convert from moles to mass or vice versa, you use g/mol.