Exam 1 Study Guide Flashcards

1
Q

Dispersion force

A

all liquids/solids experience; weakest force
- increases w/ increasing molar mass

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2
Q

London force

A

dispersion force for nonpolar species

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3
Q

dipole-dipole interaction

A
  • polar molecules
  • higher melting and boiling points
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4
Q

hydrogen bonding

A

F-H, N-H, O-H
- highest melting and boiling points

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5
Q

hydrophilic

A

water-soluble
- ions, polar molecules, H-bonds

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6
Q

hydrophobic

A

water-insoluble
- hydrocarbons (alkanes)

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7
Q

boiling point increases w/ increasing ___

A
  • increasing molar mass
  • increasing polarity
  • increases greatly w/ hydrogen bonding
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8
Q

branching disrupts ___

A

the amount of surface area molecules that interact
- decreases van der Waals interaction–>
- decreases boiling point

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9
Q

dipole-dipole interactions, dipole-induced-dipole interactions, and dipole-induced-dipole-induced interactions occur b/w what molecules?

A
  • dipole-dipole interactions: polar and polar molecule (no H-bonds)
  • dipole-induced-dipole interactions: polar and non polar
  • dipole-induced-dipole-induced interactions: nonpolar and nonpolar molecules
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10
Q

triple point

A
  • pressure and temperature at which solid, liquid and gas of a pure substance coexist in equilibrium
  • the lowest pressure at which the liquid phase can exist
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11
Q

below the triple point…

A

solid –> vapor or vapor –> solid

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12
Q

critical temperature

A

lowest temp liquid and gas coexist

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13
Q

melting point: molecular, ionic, metallic, covalent

A
  • molecular: low (lowest)
  • ionic: high
  • metallic: hard to predict
  • covalent: very high (highest)
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14
Q

conductivity: molecular, ionic, metallic, covalent

A
  • molecular: poor conductor
  • ionic: poor conductor
  • metallic: excellent conductors
  • covalent: poor conductor
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15
Q

strength: molecular, ionic, metallic, covalent

A
  • molecular: soft
  • ionic: hard but brittle
  • metallic: ductile, malleable
  • covalent: very hard and very brittle
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16
Q

sheen: molecular, ionic, metallic, covalent

A
  • molecular: dull
  • ionic: dull
  • metallic: shiny
  • covalent: dull
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17
Q

Is rate dependent upon concentration? Why or why not?

A

yes, as concentration increases, rate increases

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18
Q

What is the significance of k? Is it dependent upon pressure? Temperature?

A
  • k = rate constant
  • depends on temp (not pressure)
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19
Q

The half-life of which order reaction (0,1,2 which?) is independent of concentration?

A

1st

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20
Q

the unit of a rate constant is always

A

M^-(order-1)*S^(-1)

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21
Q

For which order reaction would reactant A be totally consumed in twice the half-life of the reaction?

A

0th order

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22
Q

For which order does the concentration of the reactant decrease by 1⁄4 in twice the half-life of the reaction?

A

1st

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23
Q

define equilibrium

A

rate forward = rate backwards
- forming reactants at same rate forming products

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24
Q

Is an elementary step the same as an elementary reaction?

A

yes

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25
Q

What is the rate-limiting step?

A
  • the slowest step
  • determines overall rate of reaction
  • Rslow = Roverall
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26
Q

what is an intermediate?

A

produced and consumed but not in overall reaction
- right –> left side (products –> reactants)

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27
Q

t/f: rate law depends on intermediates

A

FALSE (independent of intermediates, must substitute in rate expressions)

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28
Q

what is a catalyst?

A

produced and consumed but not in overall reaction
-left –> right side (reactants –> products)

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29
Q

Is concentration of catalyst allowed in a rate law (rate expression)?

A

it could be used

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30
Q

activation energy

A

minimum energy to start a reaction

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31
Q

activation energy depends on…

A

the substance (NOT temp, pressure, or concentration)

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32
Q

how does a catalyst impact activation energy?

A

decreases

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33
Q

K = ?

A

= K(forward)/K(backward)
= k1/k-1
= [products]^# / [reactants]^#

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34
Q

formation reaction

A

forming 1 mole of a compound from the 2 elements in their natural temp and pressure

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35
Q

what does a large K value mean?

A

mostly product at equilibrium, very little starting material

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36
Q

a small K value means…

A

mostly starting material, very little product

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37
Q

What quantity represents the extent of reaction?

A

how much product is made at equilibrium

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38
Q

K = 1 means…

A

molarities of reactions = molarities of products

39
Q

K < 1 means…

A

favors the reactants

40
Q

K > 1 means…

A

favors products

41
Q

atoms with lone pairs are usually more ____, and differences in electronegativity between two atoms results in ____

A

electronegative
polarity

42
Q

when are gases permanent gases at room temperature (25 dC?)

A

Tc < 25 dC

43
Q

how does polarity effect boiling point? nonpolar?

A

polarity increases boiling point
- nonpolar has lower boiling point

44
Q

polarizability depends on ____

A

molar mass (more polar = larger molar mass)

45
Q

unit for k is found by ?

A

M^-(order - 1) S^(-1)

46
Q

Rate =

A

change(concentration)/change(time)

47
Q

The activation energy of a reaction A + B → C depends upon what property?

A

the nature of reactant species

48
Q

What are minimal requirements for two molecules to react to form product?

A
  • molecules must approach with the right orientation
  • molecules must collide with minimal energy required to break bonds ( ≥ EA)
49
Q

define reaction mechanism

A

Sequence of elementary steps (in complex reaction) describe in detail how the reaction proceeds

50
Q

R overall ~ =

A

R slow

51
Q

write the rate law for given steps:

A

Roverall = Rslow
- R = k (reactants slow)^(stoichiometry)
- substitute for intermediates

52
Q

equation to solve for order “m” or “n”

A

Ln (R1/R2) = m * Ln(A1/A2)

53
Q

where is the triple point on the phase diagram? the critical point?

A

triple point- where all 3 line segments meet
critical point- end of far line

54
Q

what phase is below the line on the phase diagram? top left? top right?

A
  • bottom: gas
  • top left: solid
  • top right: liquid
55
Q

Common network covalent elements and compounds

A

common: Si, SiC, SiO2 (quartz), C (diamond), C (graphite), BN, Ge, ReB2, AIN

56
Q

UNITS for temperature in Arrhenius equation

A

KELVIN (C + 273.15)

57
Q

what substances are taken into account for the equilibrium constant expression (K)?

A

gases (g) and aqueous solutions (aq)
- not solid or liquids
- K = (products)/(reactants)

58
Q

(Ms)^-1 = what order?

A

2nd

59
Q

Le Chatelier’s Principle

A

if a system at equilibrium is disturbed by some change, then the system will shift so as to entirely or partially counteract the effect of the change

60
Q

examples of changes for le chatelier’s principle

A
  • Adding or removing gaseous reactants or products
  • Changing the volume or pressure of system
  • Changing the temp
61
Q

(LC) adding a gaseous species to the products will shift equilibrium to the

A

left

62
Q

(LC) removing a gaseous species from the products will shift equilibrium to the

A

right

63
Q

(LC) adding a gaseous species to the reactants will shift equilibrium to the

A

right

64
Q

(LC) removing a gaseous species from the reactants will shift equilibrium to the

A

left

65
Q

Le Chatelier’s principle does not include…

A
  • liquids or solid
  • a gas that doesn’t react with another species
66
Q

(LC) increasing volume will shift equilibrium to…

A

the side with more gas moles

67
Q

(LC) decreasing volume will shift equilibrium to…

A

the side with fewer gas moles

68
Q

(LC) increasing pressure will shift equilibrium to…

A

the side with fewer gas moles

69
Q

(LC) decreasing pressure will shift equilibrium to…

A

the side with more gas moles

70
Q

(Van Hoff’t) endothermic (+), raising temp shifts the equilibrium…

A

to more products

71
Q

(Van Hoff’t) endothermic (+), lowering temp shifts the equilibrium…

A

to more reactants

72
Q

endothermic reactions…

A

need energy

73
Q

exothermic reactions…

A

don’t need energy (have enough)

74
Q

(Van Hoff’t) exothermic (-), raising temp shifts the equilibrium…

A

to more reactants

75
Q

(Van Hoff’t) exothermic (-), lowering temp shifts the equilibrium…

A

to more products

76
Q

(Van Hoff’t) exothermic (-), lowering temp shifts the equilibrium…

A

to more products

77
Q

Would addition of a catalyst to a reaction increase the equilibrium constant?

A

NO- The only thing that changes an equilibrium constant is a change of temperature

78
Q

what effects the equilibrium constant value?

A

ONLY temperature

79
Q

Adding mass to one side, shifts equilibrium towards

A

The opposite side

80
Q

Relationship between pressure and volume

A

Inverse (one increases, other decreases)

81
Q

Delta (H) < 0 =
(-) delta H

A

Exothermic

82
Q

Delta(H) > 0 =
(+)

A

Endothermic

83
Q

Diatomic elements

A

Have no fear of ice cold bear
(Hydrogen, nitrogen, oxygen, iodine, chlorine, bromine)

84
Q

concentration = —/—-

A

Mol / Volume

85
Q

Reverse rate constant = (K)^?

A

K^(-1)

86
Q

Q =

A

(products)/(reactants)

87
Q

Q = K =

A

at equilibrium

88
Q

Q ≠ K =

A

not at equilibrium

89
Q

Q < K =

A

reaction moving to the right (products)

90
Q

Q > K =

A

reaction moving to the left (reactants)

91
Q

The addition of a buffer gas or of a pure solid (or pure liquid) causes ____ effect.

A

no effect

92
Q

equilibrium table: extent of the reaction = ___ units

A

x atm

93
Q

breaking bonds….

A

requires energy (endothermic)

94
Q

making bonds…

A

releases energy (exothermic)