Calculating Masses in Reactions.
Three Important Steps.
1) Write out the balanced equation.
2) Work Out Mr - Just for the two bits you want.
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, then the other.
Example: What mass of magnesium oxide is produced when 60g of magnesium is burned in the air.
Ar for Mg = 24.
1) Write our the balanced equation: 2Mg + O2 -----> 2MgO
2) Work out the relative formula masses: 2 x 24 ------> 2 x (24 + 16)
(Don't do oxygen, you don't need it) 48 ------> …