3. Apply the rule: divide to get one, then multiply to get all
( but you have to apply this first to the
substance they give information about,
and then the other one )
How to calculate reactant mass: Work out the ratio of
reactant to product (or product to reactant) for the
required situation. (You want the unknown on the top!)
Work out the ratio of reactant to product (or product to
reactant) from the masses given. Write them equal to
each other. Rearrange the equation. Work out the
answer.