Determine how much of each product (in g or L) is formed.

2.50g of aluminum metal is placed in a large container of concentrated copper (ll) suflate to produce copper metal.

2Al + 3CuSO4 ==> Al2(SO4)3 + 3Cu

1. mols Al = grams/molar mass = about 0.092 but you need to be more accurate than that.
2. Convert mols Al to mols of any other substance using the coefficients in the balanced equation. Fo example
mols Cu = mols Al x (3 mool Cu/2 mol Al) = 0.092 x (3/2) = ?
3. g product then = mols x molar mass or atomic mass as appropriate.

These three steps will do them all. In fact these three steps will do 99.9% of all of the stoichiometry problems you will have. An exta step must be added for working limiting reagent problems.