Question

To make a smore, 2 graham crackers, a piece of chocolate, and a marshmallow are needed. You have 5 graham crackers, 7 pieces of chocolate, and 5 marshmallows. Using smores as your example, explain the concepts of limiting reactant, excess reactant, and theoretical yield.

Answer 1

Limiting Reactant - The reactant in a Chemical Reaction that limits the amount of product that can be formed.

Excess Reactant - The reactant in a chemical reaction that remains when a reaction stops when the limiting reactant is completely consumed.

Theoretical Yield - The quantity of a product obtained from the complete conversion of the limiting reactant in a Chemical reaction.

I hope this helped make your question easier ^_^

Answer 2

Limiting reactant: graham crackers

Excess reactants: chocolate and marshmallows

Theoretical yield: 5/2 smores

Step-by-step explanation:

When 2 graham crackers, a piece of chocolate, and a marshmallow are combined a smore is made.

You have 5 graham crackers, the following proportions must be satisfied:

2 graham crackers/5 graham crackers = 1 piece of chocolate/x piece of chocolate

x = 1*5/2 = 5/2 pieces of chocolate reacts

2 graham crackers/5 graham crackers = 1 marshmallow/y marshmallow

x = 1*5/2 = 5/2 marshmallows reacts

But you have 7 pieces of chocolate and 5 marshmallows, then the graham crackers are the limiting reactant, that is, when all crackers react, the reaction is finished. As a consequence the excess reactants are the pieces of chocolate and the marshmallows, because at the time the reactant is completely consumed, there are still chocolate and marshmallow.

To compute the theoretical yield, the following proportion must be satisfied (the limiting reactant is used):

2 graham crackers/5 graham crackers = 1 smore/z smore

z = 1*5/2 = 5/2 smores are made