CHAPTER 9Stoichiometry

I. STOICHIOMETRY Describes the mass and mole relationships in a

chemical reaction Use it to predict the amount of product formed

or the amount of reactant needed in a particular reaction

EXAMPLES1. How many moles of each product are formed:

Sodium Chloride Sodium + Chlorine +NaCl Na Cl22 2

2.0 moles 2.0 moles 1.0 moles

4.0 moles 4.0 moles

8.0 moles

2.0 moles

1.0 moles 0.5 moles1.0 moles

8.0 moles 4.0 moles

EXAMPLES2. Sodium Chlorate Sodium Chloride + Oxygen

+NaClO3 NaCl O22 2 34.0 moles

.567 moles

6.0 moles4.0 moles

.378 moles .378 moles

EXAMPLES3. How many moles of Oxygen are produced from the

decomposition of .849 moles of Potassium Chlorate?

Potassium Chlorate Potassium Chloride + OxygenKClO3 O2KCl + 322

EXAMPLES4. How many grams of Water are produced from the

decomposition of 1.42 moles of Sodium Hydroxide?Sodium Hydroxide Sodium Oxide + Water

NaOH Na2O + H2O

2

EXAMPLES5. How many moles of Hydrogen are produced from the

reaction of 2.10 moles of Sodium with Water?

Sodium + Water Sodium Hydroxide + HydrogenNa + H2O NaOH + H22

EXAMPLES6. Determine the mass of Fluorine that must react with

Lithium to produce 12.0 grams of Lithium Fluoride.

Lithium + Fluorine Lithium Fluoride Li + F2 LiF22

II. LIMITING REACTANT The reactant that is present in least abundance

(less amount of moles) determines the amount of product formed.

Example: You need to make as many cakes as possible. Each cake requires 2 eggs, 2 cups of flour, and 1 cup of sugar. You have 6 eggs, 6 cups of sugar, and 4 cups of flour. Which is your limiting reactant (ingredient)?

EXAMPLES1. Circle the limiting reactant: NaHCO3 + HCl NaCl + H2O + CO2

Given: 1.0 mole 1.5 mole

1.0 mole 1.0 mole 1.0 mole 1.0 mole 1.0 moleActual:

Given: .475 mole .214 mole

Actual: .214 mole.214 mole .214 mole .214 mole .214 mole

Examples2. Mg + 2 HCl MgCl2 + H2

Given: 1.0 mole 1.5 mole

Actual:

Given: 2.0 mole 4.5 mole

Actual:

Examples3. 2 Al + 3 S Al2S3

Given: 4.0 mole 5.0 mole

Actual:

Examples4. If 1.00 gram of Hydrogen reacts with 6.00 grams

of Oxygen, determine the mass of product formed.