According to the law of conservation of mass, if an element A has an atomic mass of 2 mass units and element B has an atomic mass of 3 mass units, what mass would be expected for compound AB? for compound A2B3?

Question

anonymous · Answer

Well, the law of conservation of mass says pretty much what it sounds like. Basically that mass stays the same in reactants and products.

For AB you will have 1 mol A which has 2 amus and 1 mol B which has 3. Since no mass was lost in the reaction, the mass of AB is the two added, or 5 amus

For A2B3 you have 2 A's which have 2 amus each for a total of 4 amus + 3 B's which have 3 amus each for a total of 9 amus. Add them together, and its mass has a total of 13 amus

anonymous · Answer

So basically it's just a matter of adding?

anonymous · Answer

yes, but also taking into account how many of each there are. Often they will try to trick you by writing the formula like $$3AB _{2}$$
In that case, there are 3 A's and 6 B's