Download Chemistry 103: Module 4 - Avogadro's Number, Formula Mass, Percent Composition and more Exams Chemistry in PDF only on Docsity! Chem 103: Module 4 Avogadro's number - 6.022 x 10^23 atoms = 1 mole 1 u = ___ g - 1.661 x 10 ^-24 g formula mass - the sum of the average atomic masses of each atom represented in the chemical formula and is expressed in atomic mass units. --The formula mass of a covalent compound is also called the molecular mass. The chemical identity of a substance is defined by - the types and relative numbers of atoms composing its fundamental entities (molecules in the case of covalent compounds, ions in the case of ionic compounds). A compound's percent composition provides - the mass percentage of each element in the compound. calculate the formula mass of a substance by - summing the average atomic masses of all the atoms represented in the substance's formula. A mole is defined as - the amount of substance containing the same number of discrete entities (such as atoms, molecules, and ions) as the number of atoms in a sample of pure 12-C weighing exactly 12 g percent composition - the percentage by mass of each element in a compound i.e. mass X / mass compound x 100% stoichiometry - refers to the quantitative relationships between amounts of reactants and products in a chemical reaction. Combustion - a reaction in which an element or compound burns in air or oxygen --The combustion of compounds containing hydrogen and carbon (CxHy) will always produce two products: water (H2O) and carbon dioxide (CO2). --The same is true for the combustion of compounds containing hydrogen, carbon and oxygen (CxHyOz) Chemical formulas provide the - identities of the reactants and products involved in the chemical change, allowing classification of the reaction Coefficients provide the - relative numbers of these chemical species, allowing a quantitative assessment of the relationships between the amounts of substances consumed and produced by the reaction. stoichiometric factor - ratio of coefficients in a balanced chemical equation, used in computations relating amounts of reactants and products Limiting Reactant - A reactant that is totally consumed during a chemical reaction, limits the extent of the reaction, and determines the amount of product. theoretical yield - The amount of product that may be produced by a reaction under specified conditions, as calculated per the stoichiometry of an appropriate balanced chemical equation, is called the theoretical yield of the reaction
