Ch 4: Compounds and Stoichiometry Flashcards
compounds
substances composed of two or more elements in a fixed composition
molecular weight
mass (in amu) of the constituent atoms in a compound as indicated by the molecular formula
molar mass
mass of one mole of a compound; usually measured in grams per mol
gram equivalent weight
measure of the mass of a substance that can donate one equivalent of the species of interest
normality
ratio of equivalents per liter; it is related to molarity by multiplying the molarity by the number of equivalents present per mole of compound
equivalents
moles of the species of interest; equivalents are most often seen in acid-base chemistry (hydrogen ions or hydroxide ions) and oxidation-reduction reactions (moles of electrons or other ions)
law of constant composition
any pure sample of a compound will contain the same elements in the same mass ratio
empirical formula
smallest whole-number ratio of the elements in a compound
molecular formula
either same as or a multiple of the empirical formula; gives exact number of atoms of each element in a compound
percent composition by mass
determine the mass of the individual element and divide by the molar mass of the compound
combination reactions
occur when two or more reactants combine to form one product
decomposition reactions
when one reactant is chemically broken down into two or more products
combustion reactions
occur when fuel and an oxidant (typically oxygen) react, forming the products water and carbon dioxide (if the fuel is a hydrocarbon)
displacement reactions
occur when one or more atoms or ions of one compound are replaced with one or more atoms or ions of another compound
single-displacement reactions
occur when an ion of one compound is replaced with another element
double-displacement reactions
occur when elements from two different compounds trade places with each other to form two new compounds
neutralization reactions
those in which an acid reacts with a base to form a salt (and, usually, water)
balanced equations for stoichiometric calculations are found by
balancing least common atoms
balancing more common atoms like H and O
balancing charge
balancing equations can be used to find
limiting reagent, which is the reactant that will be consumed first in a chemical reaction
limiting reagent
reactant which will be consumed first in a chemical reaction
for ions, -ous endings can also be used to indicate
lesser charge
for ions, -ic endings indicate
greater charge
all monatomic anions end in
-ide
oxyanions are given a suffix to indicate how oxidized the central carbon is; those of lesser amount of oxygen are given suffix
-ite
oxyanions are given a suffix to indicate how oxidized the central carbon is; those of GREATER amount of oxygen are given suffix
-ate
oxyanions series with more than two members are given an additional level of nomenclature; species with the fewest oxygens is given the prefix ___ while GREATER amount is ___
- hypo
- per
polyatomic ions containing hydrogen denote the number of hydrogen using
____ to denote one or ____ to denote two
hydrogen or bi-
dihydrogen
form positively charged cations based on group number
metals
form negatively charged anions based on the number of electrons needed to achieve an octet
nonmetals
contain equivalents of ions from molecules that dissociate in solution
electrolytes
strength of an electrolyte depends on its degree of dissociation or
solvation
