Ch 4: Compounds and Stoichiometry

Question 1

compounds

Answer 1

substances composed of two or more elements in a fixed composition

Question 2

molecular weight

Answer 2

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

Question 3

molar mass

Answer 3

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

Question 4

gram equivalent weight

Answer 4

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

Question 5

normality

Answer 5

ratio of equivalents per liter; it is related to molarity by multiplying the molarity by the number of equivalents present per mole of compound

Question 6

equivalents

Answer 6

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)

Question 7

law of constant composition

Answer 7

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

Question 8

empirical formula

Answer 8

smallest whole-number ratio of the elements in a compound

Question 9

molecular formula

Answer 9

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

Question 10

percent composition by mass

Answer 10

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

Question 11

combination reactions

Answer 11

occur when two or more reactants combine to form one product

Question 12

decomposition reactions

Answer 12

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

Question 13

combustion reactions

Answer 13

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

Question 14

displacement reactions

Answer 14

occur when one or more atoms or ions of one compound are replaced with one or more atoms or ions of another compound

Question 15

single-displacement reactions

Answer 15

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

Question 16

double-displacement reactions

Answer 16

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

Question 17

neutralization reactions

Answer 17

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

Question 18

balanced equations for stoichiometric calculations are found by

Answer 18

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

Question 19

balancing equations can be used to find

Answer 19

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

Question 20

limiting reagent

Answer 20

reactant which will be consumed first in a chemical reaction

Question 21

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

Answer 21

lesser charge

Question 22

for ions, -ic endings indicate

Answer 22

greater charge

Question 23

all monatomic anions end in

Answer 23

-ide

Question 24

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

Answer 24

-ite

Question 25

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

Answer 25

-ate

Question 26

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 ___

Answer 26

• hypo

- per

Question 27

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

Answer 27

hydrogen or bi-

dihydrogen

Question 28

form positively charged cations based on group number

Answer 28

metals

Question 29

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

Answer 29

nonmetals

Question 30

contain equivalents of ions from molecules that dissociate in solution

Answer 30

electrolytes

Question 31

strength of an electrolyte depends on its degree of dissociation or

Answer 31

solvation