Limiting and Excess Reactant

Limiting Reactant and Percent Yield

Limiting Reactant

is the reactant that

limits the amount of the other reactant that can combine and the amount

of product that can form in a chemical reaction.

Multiple Choice

How many hamburgers you can make?

• 5

• 4

• 3

• 7

Excess Reactant

The substance that is not

used up completely in a reaction is called the excess reactant. 

Multiple Select

What are the excess reactants in the hamburger recipe?

• Bread/buns

• Meat

• Lettuce

• Cheese

Theoretical Yield

The theoretical yield is

the maximum amount of product that can be produced from a given

amount of reactant. 

In THEORY, I can get only 3 hamburgers because of the Limiting Reactant

But ACTUALLY

In real-life, in real-lab process, you will always obtain less than expected (less that you got in the stoichiometric process)

So the ACTUAL YIELD is always LESS than the THEORETICAL YIELD

You will always get a little LESS than expected

So here comes the new formula

Multiple Choice

From stoichiometric calculations, you should obtain 100 grams of NaCl in the product.

In the lab you obtained 80 grams of NaCl.

What is the Percent Yield?

• 75%

• 80%

• 90%

• 100%