2 Al + 3 S --> Al2S3

Question

In an experiment 10.0 g Al is combined with 15.0 g S. If the reaction continues until one reactant is totally consumed, which reactant would be in excess and how many grams would be unreacted?

Answer 1

Another limiting reagent problem with a twist. After you have identified the limiting reagent(LR) you know the other reagent is the one in excess (ER for excess reagent). Use the coefficients in the balanced equation to convert mols LR to mols excess reagent(ER).
mols excess reagent USED = mol LR x (?mol ER/mol LR) = mols ER used.
Now mols ER intially - mols ER used = mols ER remaining. Convert to grams by g = mols x molar mass.