Stoichiometry

Limiting Reagents

Stoichiometry

If the quantity of each reactant is given, you must determine which one is used up first. This is the Limiting Reagent

The other reactant is not completely consumed in the reaction. It is in Excess.

Stoichiometry

Like many problems in chemistry, there are multiple ways of solving these problems.

You can save yourself some work, by first identifying what you need to solve for and then choosing the appropriate method.

Don’t worry if you choose the wrong method, you’ll get to the correct answer, it will just take you a few more steps.

Stoichiometry

Types of problems:1. You want to know how much of the

excess reactant remains.2. You want to know how much product

is formed

Stoichiometry

CaCl2 (aq) + 2 AgNO3 (aq) Ca(NO3)2 (aq) + 2 AgCl(s)

65.35g 112.08g

Determine which is the LR and how much of the excess reagent remains1. Begin with either reactant; convert to moles; use your mole ratio to get to the other reactant; convert back to grams

Stoichiometry

CaCl2 (aq) + 2 AgNO3 (aq) Ca(NO3)2 (aq) + 2 AgCl(s)

65.35g 112.08g

Stoichiometry

CaCl2 (aq) + 2 AgNO3 (aq) Ca(NO3)2 (aq) + 2 AgCl(s)

65.35g 112.08g

How much product can be formed?1. Begin with either reactant; convert to moles; use the mole ratio to get to your product; convert back to grams2. This must be done for each reactant3. The reactant that produces the least amount of product is the LR

Stoichiometry

CaCl2 (aq) + 2 AgNO3 (aq) Ca(NO3)2 (aq) + 2 AgCl(s)

65.35g 112.08g