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Chemistry > Modern States Unit 2 > Flashcards

Modern States Unit 2 Flashcards

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1
Q

What is a crucial topic in chemistry that deals with the amounts of substances?

A

Stoichiometry

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2
Q

What are important concepts that help determine stoichiometric amounts

A

Molar and formula masses

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3
Q

Coefficients in chemical reactions do not indicate ratios of reactants and products in terms of what?

A

masses

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4
Q

What is calculated by multiplying the molar mass of the substance by the number of moles?

A

the mass of a substance produced

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5
Q

What is the unit of measurement for amount of substance, a quantity proportional to the number of elementary entities of a substance?

A

The mole

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6
Q

What type of reagent is the reactant that is present in the smallest amount?

A

Limiting Reagent

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7
Q

What type of reagent is whatever is remaining after the reaction?

A

Excess reagent

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8
Q

What type of reagent is the one with leftover moles after the reaction?

A

Excess reagent

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9
Q

Balancing chemical reactions involves ensuring that the numbers of each type are what?

A

are the same on both sides of the reaction

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10
Q

What type of reagent gets completely used up in the reaction?

A

Limiting Reagent

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11
Q

What type of reagent determines the outcome of the reaction?

A

Limiting Reagent

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12
Q

Coefficients in chemical reactions indicate ratios in terms of what?

A

molecules or moles

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13
Q

Coefficients in chemical reactions do not indicate what in terms of molecules or moles, not masses?

A

ratios of reactants and products

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14
Q

Aqueous solutions involve dissolving substances in what?

A

water

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15
Q

What occurs when ionic substances dissolve in water, producing more ions that conduct electricity?

A

Dissociation

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16
Q

What type of electrolytes dissociate completely?

A

Strong

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17
Q

What type of electrolytes only conduct electricity to a limited extent

A

weak

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18
Q

Understanding the formula and dissociation of substances can help calculate the what of ions in a solution

A

concentration

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19
Q

For what type of substances, the formula represents the numbers and types of atoms composing a single molecule of
the substance?

A

covalent

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20
Q

What type of compounds are composed of discrete cations and anions combined in ratios to yield electrically neutral bulk matter?

A

Ionic compounds

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21
Q

what traits are the identity of a substance is defined by?

A
  • types of atoms or ions it contains
  • the quantity of each type of atom or ion
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22
Q

How formula mass for an ionic compound is calculated in the same way as the formula mass for covalent compounds

A

by summing the average atomic masses of all the atoms in the compound’s formula

formula for ionic compound doesn’t represent composition of a discrete molecule, so it may
not correctly be referred to as the molecular mass

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23
Q

True or false

Formula mass for an ionic compound is not calculated in the same way as the formula mass for covalent.

A

False

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24
Q

The amount of product that may be produced by a reaction under specified conditions is called what?

as calculated per the
stoichiometry of an appropriate balanced chemical equation

A

theoretical yield

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25
Q

What is defined as the amount of substance containing
the same number of discrete entities as the number of atoms in a sample of pure
12C weighing exactly 12 g?

(such as atoms, molecules, and ions)

A

A mole

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26
Q

The number of entities composing a mole is a constant is properly reported with an explicit unit of “per mole,” a conveniently rounded version being What?

A

6.022 × 1023/mol

fundamental constant named Avogadro’s number (NA) or the Avogadro constant in honor of Italian scientist Amedeo Avogadro.

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27
Q

True or False

1 mole of any element contains the same number of atoms as 1 mole of any other element.

A

True

The masses of 1 mole of different elements, however, are different, since the masses of the
individual atoms are drastically different.

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28
Q

What is defined as the percentage by
mass of each element in the compound

A

percent composition

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29
Q

empirical formulas are derived from experimentally measured element masses by what three steps?

A
  1. Deriving the number of moles of each element from its mass
  2. Dividing each element’s molar amount by the smallest molar amount to yield subscripts for a tentative
    empirical formula
  3. Multiplying all coefficients by an integer, if necessary, to ensure that the smallest whole-number ratio of subscripts is obtained
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30
Q

Molecular formulas are derived how?

A

by comparing the compound’s molecular or molar mass to its empirical formula
mass

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31
Q

What is empirical formula mass ?

A

the sum of the average atomic masses of all the atoms represented in an empirical formula

If we know the molecular (or molar) mass of the substance, we can divide this by the empirical formula mass units per molecule

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32
Q

empirical formula

A

molecular or molar mass (amu or g per mol)
/
empirical formula mass (amu or g per mol)
= n formula units or molecule

33
Q

The relative amounts of reactants and products represented in a balanced chemical equation are often referred to as
what?

A

stoichiometric amounts

34
Q

The amount of product obtained is called the what?

A

actual yield

35
Q

forlmula of percent yield

A

percent yield = actual yield/
theoretical yield × 100%

36
Q

What is quantitative analysis?

A

the determination of the amount
or concentration of a substance in a sample

37
Q

he described approach to measuring vinegar strength was an early version of the analytical technique known as
what?

A

titration analysis

38
Q

A typical titration analysis involves the use of what?

A

a buret

39
Q

special dyes called what are added to the sample solutions to impart a change
in color at or very near the equivalence point of the titration

A

indicators

40
Q

the volume of titrant actually measured is called the what?

A

end point

41
Q

Name reasons why the reaction’s actual yield is smaller than the theoretical yield.

A
  1. no reaction actually ever goes 100% to completion
  2. there is experimental error in recovering all of the product.
  3. the chemical reaction is not 100% efficient
42
Q

What is a way were a sample is subjected to some treatment that causes a change in the physical
state of the analyte that permits its separation from the other components of the sample?

A

gravimetric analysis

43
Q

The elemental composition of hydrocarbons and related compounds may be determined via a gravimetric method known as what?

A

combustion analysis

44
Q

In a what, a weighed sample of the compound is heated to a high temperature under a stream of oxygen gas, resulting in its complete combustion to yield gaseous products of known
identities.

A

combustion analysis

45
Q

The substances undergoing reaction are called what and their formulas are placed on which side of the
equation.

A

reactants

the left

46
Q

The substances generated by the reaction are called what, and their formulas are placed on which sight
of the equation

A

products

the right

47
Q

The relative numbers of reactant and product species are represented by what?

(numbers placed immediately to the left of each formula)

A coefficient of 1 is typically omitted.

A

coefficients

48
Q

True or false

Substances with relatively large solubilities are said to be soluble in water

A

True

49
Q

balanced meaning that equal numbers of atoms for each element
involved in the reaction are represented on the reactant and product sides

A

meaning that equal numbers of atoms for each element
involved in the reaction are represented on the reactant and product sides

50
Q

What are ions whose presence is required to maintain charge neutrality

A

spectator ions

51
Q

Define solubility

A

The extent to which a substance may be dissolved is quantitatively expressed

52
Q

What reaction is one in which dissolved substances react to form one (or more) solid products.

A

precipitation

Many reactions of this type involve the exchange of ions between ionic compounds in aqueous solution and are sometimes referred to as double displacement, double replacement, or metathesis reactions.

53
Q

A substance will precipitate when solution conditions are what?

A

conditions are
such that its concentration exceeds its solubility

54
Q

Substances with relatively low solubilities are said to be what and these are the substances that readily precipitate from solution?

A

insoluble

55
Q

What is a substance that will dissolve in water to yield hydronium ions

A

acid

56
Q

Acids that completely dissolve in water to yield hydronium ions are called what?

A

strong acid

57
Q

What only partially react with water, leaving a large
majority of dissolved molecules in their original form and generating a relatively small amount of hydronium ions

A

weak acids

58
Q

hydroxides that completely dissociate in
water, are considered what?

A

strong bases

59
Q

What is a specific type of acid-base reaction in which the reactants are an acid and a base, the
products are often a salt and water, and neither reactant is the water itself

A

A neutralization reaction

60
Q

These equations show that Na atoms lose electrons while Cl atoms (in the Cl2 molecule) gain electrons, the “s”
subscripts for the resulting ions signifying they are present in the form of a solid ionic compound.

A

half-reaction

61
Q

species that is oxidized

A

reducing agent

62
Q

species that is reduced

A

oxidizing agent

63
Q

1.loss of electrons

2.gain of electrons

A

oxidation
reduction

64
Q

What is an element in
a compound is the charge its atoms would possess if the compound was ionic

A

oxidation number (or oxidation state)

65
Q

What are those in which one or more elements involved undergo a change in oxidation
number

A

Oxidation-reduction (redox) reactions

66
Q

What reactions are redox reactions in which an ion in solution is displaced (or
replaced) via the oxidation of a metallic element?

A

Single-displacement (replacement)

67
Q

Define:

spontaneous process

A

a process that occurs under specified conditions without the requirement of energy from some external source

The formation of a solution is an example of a spontaneous

68
Q

What is the thing that is produced when the strengths of the intermolecular forces of attraction between solute and solvent species in a solution are no
different than those present in the separated components, the solution is formed with no accompanying energy change?

A

an ideal solution

69
Q

What is a stepwise process
in which energy is consumed to overcome solute-solute and solvent-solvent attractions (endothermic processes) and released when solute-solvent attractions are established?

A

the formation of a solution

70
Q

When some substances are dissolved in water, they undergo either a physical or a chemical change that yields ions
in solution. These substances constitute an important class of compounds called what?

A

electrolytes

71
Q

Substances that do not
yield ions when dissolved are called what?

A

nonelectrolytes

72
Q

If the physical or chemical process that generates the ions is essentially 100% efficient (all of the dissolved compound yields ions), then the substance is known as a what?

A

strong electrolyte

73
Q

If only a relatively small fraction of the dissolved substance undergoes the ion-producing process, it is
called a what?

A

weak electrolyte

74
Q

The electrostatic attraction between
an ion and a molecule with a dipole is called what?

A

an ion-dipole attraction

75
Q

When ionic compounds dissolve in water, the ions in the solid separate and disperse uniformly throughout the solution
because water molecules surround and solvate the ions, reducing the strong electrostatic forces between them. This
process represents a physical change known as what?

A

dissociation

76
Q

The solubility of a solute in a particular solvent is the maximum concentration that may be achieved under given
conditions when the what happens?

A

dissolution process is at equilibrium

77
Q

When a solute’s concentration is equal to its solubility, the solution is said to be what?

A

saturated

78
Q

If the solute’s concentration is less than its solubility, the solution is said to be what?

A

unsaturated

Chemistry (14 decks)

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