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Section 1: Defining StoichiometryChapter 8: Quantities in Chemical Reactions

Learning Goals0Describe the types of relationships indicated by a balanced chemical equation.

0State the mole ratios from a balanced chemical equation.

Particle and Mole Relationships0Chemical reactions stop when

one of the reactants is used up.0Stoichiometry is the study of

quantitative relationships between the amounts of reactants used and amounts of products formed by a chemical reaction.

Particle and Mole Relationships0Using stoichiometry, we can:

0Predict the amounts of products that form in a chemical reaction based on the amounts of reactants

0Predict how much of the reactants are necessary to form a given amount of product

Particle and Mole Relationships

0Predict how much one reactant is required to completely react with another reactant.

Example0 Interpret the equation for the

combustion of propane (C3H8) in terms of representative particles, moles, and mass.

C3H8 + 5O2 3CO2 + 4H2O

Particle and Mole Relationships0A mole ratio is a ratio between the

numbers of moles of any two substances in a balanced equation.

0The number of mole ratios that can be written for any equation is (n)(n – 1) where n is the number of species in the chemical reaction.

Practice0Determine all possible mole ratios for the following chemical equations. Balance the equations if needed.

Practice0 Al(s) + O2(g) Al2O3(s)

Practice0 Fe(s) + H2O (l) Fe3O4(s) +

H2(g)