4.1: stoichiometry: chemical proportions

introduction to stoichiometry

chemical equations

• display the formulas of the reactants and the products
• display how much of each reactant and product participate in the reaction
• enable us to determine how much product we can get from a given quantity of reactants
• the coefficients in a balanced equation indicate the relative number of molecules

types of formulas

• empirical formula: the smallest whole-number ratio of atoms present; the simplest formula of a compound
• molecular formula: the actual formula of a compound

molarity and stoichiometry

• mole ratio: the ratio of the number of moles in one substance to the number of moles in another substance in a balanced chemical equation
    * in a balanced equation, there can be several mole ratios
    * the mole ratio is a conversion factor/proportion that lets us calculate the relative masses of reactants and/or products
    * like a bridge between the different substances in a balanced chemical equation
    * always balance the equations before doing mole ratios etc.!
• stoichiometry: the process of using a balanced chemical equation to calculate the relative masses of reactants and products involved in a reaction