A chemist carries out this reaction in the laboratory, using…

A chemist carries out this reaction in the laboratory, using 4.31 grams of zinc and an excess of sulfur: Zn + S –> ZnS From the balanced equation, she calculates that she should obtain 6.41 grams of zinc sulfide.  However, she isolates only 5.01 g of product.  What is her percent yield for this reaction?

Rust has the formula Fe2O3 and it’s made from iron metal rea…

Rust has the formula Fe2O3 and it’s made from iron metal reacting with oxygen over time.  Assume you had a [x] g block of pure iron metal than fully oxidized to rust and the mass of that product was [y] g.  What must have been the mass of oxygen that initially reaction with pure iron?