Stoichiometry: Limiting Reactant Ms. Samayoa Birmingham Community Charter High School Chemistry

Learning Objective: Students will be able to identify a limiting reactant and excess reactants from a set of reactants. Academic Vocabulary: limiting reactant and excess reactant

Limiting Reactants Analogy To understand limiting reactants, let’s first observe the parts of a burger

Limiting Reactants Analogy To make a burger you need: 1 bun 1 slice of cheese 1 patty 1 lettuce leaf Write the “recipe” for a burger in chemical equation form and identiffy the reactants and the products

Recipe into Chemical Equation 1 bun + 1 slice of cheese + 1 lettuce leaf + 1 patty  1 burger

Limiting Reactants Analogy Discuss with a partner what is the greatest number of burgers that can be made with the following number of ingredients

Limiting Reactant Analogy Despite there being 4 buns, 6 slices of cheese, and 5 patties, we can only make 3 burgers because there are only 3 lettuce leafs The lettuce leaf is known as the limiting reactant

Limiting Reactant The limiting reactant is the first reactant that is used up in a reaction When the limiting reactant is all used up, no more product can form, and the reaction stops

Limiting Reactant Analogy After making the burgers, the ingredients left over are buns, slices of cheese, and patties Because they are left over, they are known as excess reactants

Excess Reactants Excess reactant is what is left over after the reaction stops because the limiting reactant got all used up

Check for Understanding Below is the recipe to make a ham and cheese sandwich: 1 slice of ham + 1 slice of cheese + 2 slices of bread  1 ham&cheese sandwich If I had 3 slices of ham, 4 slices of cheese, and 4 slices of bread, which ingredient will be my limiting reactant and which ingredient will be my excess reactant?

S’mores Lab

Example Problem 2H2 + O2  2H2O If you start with 10 g of H2 and 5 g of O2, determine the limiting reagent.

Check for Understanding 4Fe + 3O2  2Fe2O3 If you start with 10 g of Fe and 5 g of O2, determine the limiting reagent.