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General Chemistry MCAT > Compounds and Stoichiometry > Flashcards

Compounds and Stoichiometry Flashcards

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1
Q

Molecule:

A

combination of two or more atoms held together by covalent bonds

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2
Q

Formula unit:

A

representing the emperical formula of the compound

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3
Q

Formula weight:

A

found by adding up the atomic weights of the constituent ions according to its empirical formula

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4
Q

Atomic weight:

A

a weighted average of the masses of the naturally occuring isotopes of an element not their weights

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5
Q

Molecular weight:

A

the sum of the atomic weights of all the atoms in a molecule

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6
Q

Mole

A

quantity of any substance equal to the number of particles that are found in 12 grams of carbon 12

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7
Q

Avogadro’s number (NA):

A

6.022 X 10^23 mol^-1

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8
Q

Molar mass:

A

The mass in grams of one mole of an element or compound

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9
Q

Moles =

A

mass of sample (g) / molar mass (g/mol)

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10
Q

Equivalents:

A

A mole of charge in the form of electrons, protons, ions or other measerable quantities that are produced by a substance

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11
Q

Gram equivalent weight=

A

molar mass/n

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12
Q

Equivalents=

A

Mass of compound (g)/ gram equivalent weight (g)

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13
Q

Normality (N):

A

A concentration unit equal to the number of equivalents per liter of solution

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14
Q

Molarity=

A

Normality/n

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15
Q

Calculate the molar masses of the following substances: NaBr

A

23 + 80 = 103 g/mol

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16
Q

Calculate the molar masses of the following substances: SrCl2

A

87.6 + (2 x 35.5) = 87.6 + 71 = 158.6 g/mol

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17
Q

Calculate the molar masses of the following substances: C6H12O6

A

(6x12) + (12 x 1) + (6 x 16) = 180 g/mol

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18
Q

Calculate the number of moles in 100g of each of the following substances: NaBr

A

100g /103 g/mol = 0.97 moles

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19
Q

Calculate the number of moles in 100g of each of the following substances: SrCl2

A

100g/ 158.6 g/mol = 0.625 moles

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20
Q

Calculate the number of moles in 100g of each of the following substances: C6H12O6

A

100g/ 180 g/mol = 0.555 moles

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21
Q

How do the number of molecules in 18 g of H2O compare to the number of formula units in 58.5 g of NaCl?

A

both values equal one mole of the given substance. The number of entities in a mole is always the same (6.02 x 10^23)

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22
Q

Determine the normality of the folowing solutions. (Species of interest is H+) H3PO4

A

N = M x [equivalents/ mole]
0.25 M x [ (3 equiv H+)/ mol H3PO4] = 0.75 N H3PO4

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23
Q

Structural formulas:

A

the graphic representation of a molecule depicting how its atoms are arranged

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24
Q

Law of constant composition:

A

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

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25
Q

Emperical formula:

A

gives the smallest whole number ratio of atoms of each type in the compound

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26
Q

Molecular formula:

A

exact number of atoms in an element in the compound and is a multiple of the emperical formula

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27
Q

Percent composition:

A

the percent of a specific compound that is made up of a given element

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28
Q

Percent composition:

A

[Mass of element in formula/ molar mass] x 100

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29
Q

What are some similarities and differences between molecular and emperical fomulas?

A

both the molecular and emperical formulas contain the same elements in the same ratios. They differ in that molecular formulas give the actual number of atoms of each element in the compound; emperical formulas give only the ratio and therefore may or maynot give the actual number of atoms

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30
Q

Combination reaction:

A

has two or more reactants forming one product

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31
Q

Example of a combination reaction:

A

2 H2 (g) + O2 (g) -> 2 H2O (g)

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32
Q

Decomposition reaction:

A

opposite of a combination reaction: a single reactant breaks down into two or more products, usually as a result of heating, high frequency radiation ot electrolysis

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33
Q

Example of a decomposition reaction:

A

2HgO (s) -Δ-> 2Hg (l) + O2 (g)

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34
Q

Combustion reaction:

A

a special type of reaction that involves fuel (usually a hydrocarbon), and an oxidant (normally oxygen)

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35
Q

Example of a combustion reaction:

A

CH4 + 2O2 -> CO2 + 2H2O

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36
Q

Single-displacement reaction:

A

occurs when an atom or ion in a compound is replaced by an atom or ion of another element

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37
Q

Example of a single-displacemnt reaction:

A

Cu (s) + AgNO3 (aq) -> Ag (s) + CuNO3 (aq)

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38
Q

Double-displacement reaction:

A

elements from two different compounds swap places with each other to form two new compounds

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39
Q

Another name for double-displacement reaction:

A

metathesis reaction

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40
Q

Example of double-displacement reaction:

A

CaCl2 (aq) + 2 AgNO3 (aq) -> Ca(NO3)2 (aq) + 2 AgCl (s)

41
Q

Neutralization reactions:

A

Specific type of double displacement reaction, in which an acid reacts with a base to produce a salt and usually water.

42
Q

Example of a neutralization reaction:

A

HCl (aq) + NaOH (aq) -> NaCl (aq) + H2O (l)

43
Q

Describe in words what occurs when Zn(NO3)2 is dissolved in (NH4)2S:

A

Ammonium cations swap places with (or displace) zinc cations yeilding ammonium nitrate and zinc (II) sulfide. Zinc (II) sulfide then precipitates out of the solution as a solid salt

44
Q

2 H2 + O2 ->

A

2 H2O (combination)

45
Q

Al(OH)3 + H3PO4 ->

A

3 H2O + AlPO4 (Neutralization; type of double-displacement)

46
Q

2 H20 -electricity->

A

2 H2 + O2 (decomposition)

47
Q

NaNO3 + CuOH ->

A

NaOH + CuNO3 (Double-displacement; metathesis)

48
Q

Zn + AgCl ->

A

ZnCl + Ag (Single-displacement)

49
Q

Laws of conservation of mass:

A

The law stating that in a given reaction, the mass of the products is equal to the mass of the reactions

50
Q

Laws of conservation of charge:

A

The law stating that, in a given reaction, the charge of ions in the products is equal to the charge of ions in the reactants

51
Q

Balance the reaction:
____ Fe + ____ Cl -> _____FeCl3

A

2, 3, 2

52
Q

Balance the reaction:
____Zn + ___HCl -> ____ZnCl2 + ____H2

A

1, 2, 1, 1

53
Q

Balance the equation:
_____C5H12 + ____O2 -> ____CO2 + ____H2O

A

1, 8, 5, 6

54
Q

Balance the equation:
____Pb(NO3)2 + ____AlCl3 -> ____PbCl2 + ____Al(NO3)3

A

3, 2, 3, 2

55
Q

1 mole of any ideal gas at STP = ____ L

A

22.4

56
Q

1 mole of any substance = ________particles

A

6.02 x 10^23

57
Q

1 mole of any substance = its ________ in grams from the periodic table

A

molar mass

58
Q

Limiting reagent (or reactant):

A

the reactant that is used up or consumed first in a reaction

59
Q

Excess reagent (or reactant):

A

The reactants that remain after all the limiting reagent is used up

60
Q

Yield:

A

the amount of product predicted or actually obtained when a reaction is carried out

61
Q

Theoretical yield:

A

the maximum amount of the product that can be generated as predicted from the balanced equation

62
Q

Actual yield:

A

the amount of product one actually obtains during the reaction

63
Q

Percent yield =

A

actual yield/theoretical yield x 100

64
Q

Balance the equation:
____ Na (s) + ___ O2 (g) -> ____Na2O (s)

A

4, 1, 2

65
Q

If 46 g Na and 32 g O2 are provided, find the maximum number of moles od sodium oxide produced
4 Na + O2 -> 2Na2O

Identify the limiting reagent , and find the mass of the excess reagent left over once the reaction has run to completion

A

46g Na x [1 mol Na/23 g Na] = 2 mol Na
32 g O2 x [1 mol O2 / 32g O2] = 1 mol O2
Because 4 sodium atoms are needed for every 1 oxygen molecule, sodium will run out first. To determine the amount of Na2O formed
2 mol Na x [2 mol Na2O/ 4 mol Na] = 1 mol Na2O

2 mol Na x [ 1 mol O2/ 4 mol Na] = 0.5 mol O2
1 - 0.5 = 0.5 mol of O2 remaining
0.5 mol O2 x [32g O2/ 1 mol O2] = 16g

66
Q

Be(OH)2 is produced when water reacts with BeO. Starting with 2.5 kg BeO in excess water, and producing 1.1 kg Be(OH)2, what is the percent yield of this reaction?

A

BeO + H2O -> Be(OH)2
2500 g BeO x [1 mol BeO / 25 g BeO][1 mol Be(OH)2/ 1mol BeO][43 g Be(OH)2/ 1 mol Be(OH)2] = 4300 g Be(OH)2
Percent yield = 1100g/4300g x 100% = 25.6%

67
Q

NO2-

A

Nitrite

68
Q

NO3-

A

Nitrate

69
Q

SO3^2-

A

Sulfite

70
Q
A
70
Q

SO4^2-

A

Sulfate

71
Q

ClO-

A

Hyperchlorite

72
Q

ClO2-

A

Chlorite

73
Q

ClO3-

A

Chlorate

74
Q

ClO4-

A

Perchlorate

75
Q

HCO3-

A

bicarbonate (hydrogen carbonate)

76
Q

HSO4-

A

bisulfate (hydrogen sulfate)

77
Q

H2PO4-

A

dihydrogen phosphate

78
Q

NH4+

A

Ammonium

79
Q

C2H3O2-

A

Acetate

80
Q

CN-

A

Cyanide

81
Q

MnO4-

A

Permanganate

82
Q

SCN-

A

Thiocyanate

83
Q

CrO4^2-

A

Chromate

84
Q

Cr2O7^2-

A

Dichromate

85
Q

BO3^3-

A

Borate

86
Q

Electrolytes:

A

solutes that enable solutions to carry currents

87
Q

Solvate:

A

dissolve

88
Q

Label the following as electrolytes or nonelectrolytes:
CH4, HCl, MgBr2, Sucrose

A

Electrolytes: HCl and MgBr2
Nonelectrolytes: Sucrose and CH4

89
Q

Identify the following ion as a cation or anion and provide the formula or chemical symbol: Phosphate

A

Anion PO4^3-

90
Q

Identify the following ion as a cation or anion and provide the formula or chemical symbol: Hypochlorite

A

Anion ClO-

91
Q

Identify the following ion as a cation or anion and provide the formula or chemical symbol: Ammonium

A

Cation NH4+

92
Q

Identify the following ion as a cation or anion and provide the formula or chemical symbol: Phosphide

A

Anion P^3-

93
Q

Identify the following ion as a cation or anion and provide the formula or chemical symbol: Bicarbonate

A

Anion HCO3-

94
Q

Identify the following ion as a cation or anion and provide the formula or chemical symbol: Nitrate

A

Anion NO2-

95
Q

Identify the following ion as a cation or anion and provide the formula or chemical symbol: Chromium (II):

A

Cation Cr^2+

96
Q

Which of the following best describes ionic compounds?

A

Ionic compounds are three-dimentional arrays of charged particles

97
Q

Which of the following compounds has a formula weight between 74 and 75 grams per mole?

A

KCl

General Chemistry MCAT (7 decks)

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