Ch 4: Compounds and Stoichiometry Flashcards Preview

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Flashcards in Ch 4: Compounds and Stoichiometry Deck (31):
1

compounds

substances composed of two or more elements in a fixed composition

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molecular weight

mass (in amu) of the constituent atoms in a compound as indicated by the molecular formula

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molar mass

mass of one mole of a compound; usually measured in grams per mol

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gram equivalent weight

measure of the mass of a substance that can donate one equivalent of the species of interest

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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

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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)

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law of constant composition

any pure sample of a compound will contain the same elements in the same mass ratio

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empirical formula

smallest whole-number ratio of the elements in a compound

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molecular formula

either same as or a multiple of the empirical formula; gives exact number of atoms of each element in a compound

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percent composition by mass

determine the mass of the individual element and divide by the molar mass of the compound

11

combination reactions

occur when two or more reactants combine to form one product

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decomposition reactions

when one reactant is chemically broken down into two or more products

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combustion reactions

occur when fuel and an oxidant (typically oxygen) react, forming the products water and carbon dioxide (if the fuel is a hydrocarbon)

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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

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single-displacement reactions

occur when an ion of one compound is replaced with another element

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double-displacement reactions

occur when elements from two different compounds trade places with each other to form two new compounds

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neutralization reactions

those in which an acid reacts with a base to form a salt (and, usually, water)

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balanced equations for stoichiometric calculations are found by

balancing least common atoms
balancing more common atoms like H and O
balancing charge

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balancing equations can be used to find

limiting reagent, which is the reactant that will be consumed first in a chemical reaction

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limiting reagent

reactant which will be consumed first in a chemical reaction

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for ions, -ous endings can also be used to indicate

lesser charge

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for ions, -ic endings indicate

greater charge

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all monatomic anions end in

-ide

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oxyanions are given a suffix to indicate how oxidized the central carbon is; those of lesser amount of oxygen are given suffix

-ite

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oxyanions are given a suffix to indicate how oxidized the central carbon is; those of GREATER amount of oxygen are given suffix

-ate

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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

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polyatomic ions containing hydrogen denote the number of hydrogen using
____ to denote one or ____ to denote two

hydrogen or bi-
dihydrogen

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form positively charged cations based on group number

metals

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form negatively charged anions based on the number of electrons needed to achieve an octet

nonmetals

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contain equivalents of ions from molecules that dissociate in solution

electrolytes

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strength of an electrolyte depends on its degree of dissociation or

solvation