CHEM 0110 Chapter Notes - Chapter 3: Stoichiometry, Reagent, Limiting Reagent
Document Summary
Chapter 3: calculations with chemical formulas and equations. Section 1 molecular mass and formula mass. Molecular mass (mm): the sum of the atomic masses of all the atoms in a molecule of the substance: the average mass of a molecule of that substance, expressed in atomic mass units. Formula mass (fm): the sum of the atomic masses of all atoms in a formula unit of the compound. Section 2 the mole concept: chemist have adopted the mole concept as a convenient way to deal with the enormous numbers of molecules or ions in the samples they work with. 1 mole of ethanol equals 6. 022 x 1023 ethanol molecules. In using the term mole for ionic substances, we mean the number of formula units of the substance. Ex: a mole of sodium carbonate na2co3 is a quantity containing 6. 022 x 1023 units. But each formula unit of na2co3 contains two na+ ions and one co3.
