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AP Chemistry > chapter 3: equations, the mole, and chemical formulas > Flashcards

chapter 3: equations, the mole, and chemical formulas Flashcards

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1
Q

stochiometry: the study of …. relationships involving the

A

quantitative; substances in chemical reactions

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2
Q

knowledge of … is central to chemistry

A

how different substances react

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3
Q

equations compactly describe

A

chemical changes

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4
Q

Reactants are the substances that are

A

consumed

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5
Q

product is the substance/substances that are

A

formed

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6
Q

chemical equation describes the .. and … of … and … in a chemical reaction

A

identities; relative amounts; reactants; products

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7
Q

balanced equation is consistent with the

A

law of conservation of mass

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8
Q

coefficient represents the number of …

A

units of each substance involved in the equation

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9
Q

use the lowest possible

A

coefficients when balancing

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10
Q

do not alter the subscripts in any of the substances when

A

balancing equations

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11
Q

fractional coefficients are generally avoided because a

A

fraction of a molecule cannot exist

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12
Q

(symbols) s

A

solid

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13
Q

(symbols) l

A

liquid

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14
Q

(symbols) g

A

gas

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15
Q

(symbols) aq

A

substances dissolved in water (aqueous solution)

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16
Q

polyatomic ions behave as a … on both sides of the reaction, and are balanced as a …

A

single unit; single unit

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17
Q

three types of reactions:

A

neutralization, combustion of organic compounds, oxidation-reduction

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18
Q

the fourth common type of reaction is

A

precipitation

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19
Q

(acids and bases) simplest definition of an acid: any substance that dissolves in water and

A

yields the hydrogen cation

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20
Q

(acids and bases) acids are generally …., but when they dissolve in water they …

A

molecular compounds; ionize

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21
Q

(acids and bases) ionization: when molecular compounds

A

separate into ions in solution

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22
Q

(acids and bases) the hydrogen cation can also be written as

A

H3O+ (hydronium ion)

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23
Q

(acids and bases) writing the hydronium ion indicates that the hydrogen cation is associted with a …, and that bare H+ ions are not ….

A

water molecule; present in solution

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24
Q

(acids and bases) in reaction stoichiometry, the … representation is preferred becaue it …

A

H+; simplifies equations

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25
Q

(acids and bases) the simplest definition of a base: any substance that produces

A

hydroxide anion in water

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26
Q

(acids and bases) the most common bases are the hydroxides of elements in groups

A

1 and 2

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27
Q

(acids and bases) the eequtions for acids and bases dissolving in water show

A

charged species

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28
Q

(acids and bases) when you write an equation that contains charged species, the sume of the charges on each side of the equation

A

must be the same, along with the number of atoms

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29
Q

(acid-base reactions: neutralization) neutralization: the reaction of an acid with a base yields

A

water and the respective salt

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30
Q

(acid-base reactions: neutralization) a salt is an ionic compound composed of a

A

cation from a base and an anion from an acid

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31
Q

(acid-base reactions: neutralization) the number of hydrogen ions contributed by the acid and the number of hydroxide ions contributed by the base are equal to … and to the …

A

each other; number of water molecules formed

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32
Q

(combustion reactions) combustion reaction is the process of …, typically involves reaction with …

A

burning; oxygen

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33
Q

(combustion reactions) assume that the products of the combustion of organic compounds that contain only carbon, hydrogen, and oxygen are always

A

CO2 and H2O

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34
Q

(combustion reactions) depending on how the reaction is carried ou, the water molecules could be in either the

A

gas of the liquid state

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35
Q

(oxidation-reduction reactions) combustion reactions are a special class of chemical reactions known as

A

oxidation-reduction reactions

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36
Q

(oxidation-reduction reactions) oxidation refers to the … of electrons by a substance

A

loss

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37
Q

(oxidation-reduction reactions) reduction refers to the … of electrons by a substance

A

gain

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38
Q

(oxidation-reduction reactions) oxidation-reduction reaction is one in which electrons are

A

transferred from one species to another

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39
Q

(oxidation-reduction reactions) in all oxidation-reduction reations, some atoms are .. and some are ..

A

oxidized; reduced

40
Q

(oxidation-reduction reactions) we often need to identify which compounds are oxidized and which are reduced to understand the … of the reaction, and to help … complicated reactions

A

chemistry; balance

41
Q

(oxidation-reduction reactions) oxidation numbers are a bookkeeping method. They are … numbers assigned to … based on a set of rules

A

integer; atoms in molecules or ions

42
Q

(oxidation-reduction reactions) an atom in its elemental state has an oxidation number of

A

zero

43
Q

(oxidation-reduction reactions) monatomic ionis in ionic compounds have an oxidation number equal to the

A

charge of the ion

44
Q

(oxidation-reduction reactions) fluorine always has the ox number

A

-1

45
Q

(oxidation-reduction reactions) oxygen is generally

A

-2

46
Q

(oxidation-reduction reactions) hydrogen combined with a nonmetal is generally… and … when combined with metals

A

+1; -1

47
Q

(oxidation-reduction reactions) halogens are generally

A

-1

48
Q

(oxidation-reduction reactions) all other atoms are assigned oxidation numbers so that the sum of the oxidation numbers for all of the atoms in a species is equal to the

A

charge of the species

49
Q

(oxidation-reduction reactions) to determine which species are oxidized/reduced, wee always start with

A

assigning oxidation numbers

50
Q

one mole is equal to the number of atoms in exactly

A

12 grams of the carbon-12

51
Q

the mole is the … of the quantity “amount of a substance”

A

unit

52
Q

the number of atoms in 12 g of carbon-12 was experimentally measured and found to be

A

6.022 x 10^23 atoms

53
Q

6.022 x 10^23 is known as

A

avogadro’s number

54
Q

thus, 1 mol of anything has … of those things

A

6.022 x 10^23

55
Q

balanced chemical euations are balanced in terms of …, as well as molecules

A

moles

56
Q

the molar mass (M) of any atom, molecule, or compound is the mass in grams of

A

one mole of that substance

57
Q

thr molar mass of an element is numerically equal to the

A

atoic mass and molecular mass and formula mass

58
Q

the molar mass of a substance is used to convert between …

A

mass (in grams) and amount (in moles)

59
Q

when a new compound is discovered, one of the first tests done may be to determine its

A

percent composition

60
Q

the mass percentage of each element ina compound is calculated from the

A

chemical formula and the atomic masses of each eelemtn

61
Q

the percentage composition of a compound can be based on its …. as well as on its …

A

empiricial formula; molecular formula

62
Q

by reversing the mass percentage calculation, chemists can calculate the … of a newly prepared compound

A

empirical formula

63
Q

combustion analysis: determines the quantity of … and … in a sample of an

A

carbon; hydrogen; organic compound

64
Q

This process involves burning a sample in excess …oxygen and determining the amount of …and …generated

A

oxygen; CO2; H2O

65
Q

The percentage of carbon and hydrogen in the sample can be calculated from the

A

measured masses of CO2 and H2O

66
Q

in combustioin nalysis, the msses of each of the elements present, is not determined

A

directly

67
Q

the first step in determining a molecular formula is to experimentally determine the

A

empirical formula

68
Q

the empirical formula can be determined from either the … or … of the elements in a sample

A

masses; mass percentages

69
Q

this calculation yields only the empirical formula, because the composition by mass is based only on the relative number of … of each element in the compound

A

atoms

70
Q

the empirical formula is usually al you need to describe the composition of a

A

ionnic comound

71
Q

dditional experimental information is needed tod etermine the correct formula of a

A

molecular compound

72
Q

to calculate the relative number of moles, we need to convr tthe mass of each element into the

A

moles of atoms of that eleemnt

73
Q

procss for determining the empirical formula: composition to moles of each element by using …. to the empricial formula by …

A

the moar mass of elements; dividng by the smallest number

74
Q

empirical formulas are often determined from the results of experiments that provid

A

mass percentage composition

75
Q

if the composition is given as percentages, assum ethat a … sample has been analyzed

A

100.0 g

76
Q

to calculate the molecular formula from the empirical formula, we must know the … of the compound from experiment

A

molar mass

77
Q

the molecular formula must be a whole-number multiple of the …, where n is the number of times the empirical formula occurs in the ..

A

empirical formula; molecular formula

78
Q

n is calculated as follows: n =

A

molar mass of compound/ molar mass of empirical formula

79
Q

chemical equations express …

A

stoichiometry

80
Q

the coefficients of the balanced chemical equation relate amounts of each substance in the equation to any

A

other substance in the equation

81
Q

chemical equations quantitaively expres stochiometric relationships in both numbers of … and in …

A

molecules; moles

82
Q

(proedure for using an equation to calculate mass of product/reactnt in chemical reaction) write the balanced

A

hemical equation

83
Q

(proedure for using an equation to calculate mass of product/reactnt in chemical reaction) start with the given mass of one substance annd calculate … of this substanc

A

the number of moles

84
Q

(proedure for using an equation to calculate mass of product/reactnt in chemical reaction) use the coefficients of the balaned equation to calculate the moles of the … from the moles of the …

A

desired substance; given substance

85
Q

(proedure for using an equation to calculate mass of product/reactnt in chemical reaction)calculate the mass of the …

A

desired substance

86
Q

theoretical yield is the maximum quantity of product that can be obtained from a …, based on the amounts of …

A

chemical reaction; starting materials

87
Q

limiting reactant: the reactant that is completely … when the chemical reaction occurs

A

consumed

88
Q

when we calculate the amount of product formed, the calculation must be based on the …, not the reactants that are present in excess

A

limiting reactant

89
Q

the limiting reactant is the one that yields the .. of any one product

A

smallest amount

90
Q

sometimes … occur and consume some starting material without forming the expeced product

A

side reactions

91
Q

actual yield: mass of product … from a reaction, always .. than the theoretical yield

A

isolated; less

92
Q

percent yield =

A

actual yield/ theoretical yield x 100%

93
Q

laboratory workers occasionally observe an actual yield that is greater than the theoretical yeield because the desired substance may be … by other products or by ..

A

contaminated; excess reactants

94
Q

any time the actual yield exceeds the theoretical yield, further investigation must be done to

A

determine the source of error

95
Q

sometimes the result of a chemical reactiondepends on an

A

excess of one or more reactants

96
Q

an excess of one or more reactants can usually aoid

A

undesirable side products

97
Q

in other cases, an excss of certain reactants may be needed to… or to … it takes for the reaction to occur

A

increase the yield; shorten the length of time

AP Chemistry (24 decks)

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