Magnesium combines with oxygen to form magnesium oxide. If 15.14 g of magnesium reacts completely with 7.68 g of oxygen, what is the percent by mass of oxygen in magnesium oxide?

Question

aaronq · Answer

add up the two values to get a total mass.

then divide each component by the total and multiply by 100 to get a percent value.

anonymous · Answer

So i would do 15.4 + 7.68 = 23.08 then divide what?

aaronq · Answer

divide each component (each individual mass) by the total and multiply by 100 to get a percent value.