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ALTIUS > Chemistry 1 > Flashcards

Chemistry 1 Flashcards

1
Q

On a pressure vs. volume graph, where is “PV work” done?

A

The area UNDER the curve

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1
Q

K+MnO​42-

What is oxidation state of Mn?

A

+7

  • O= -2 x 4, so -8
  • K= +1
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2
Q

∆G=∆H-T∆S

If:

  • ΔH is +
  • ΔS is +

What is the sign of ∆G?

A
  • ∆H is unfavorable
  • ∆S is favorable

∆G is dependent on Temperature!

Will be favorable (-) ONLY if Temp is high enough

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3
Q
  • Define “Radiation”
    • give an example
A

Electromagnetic (EM) waves emitted from hot body into surrounding environment

Ex: a black car on a hot day emits heat

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4
Q

HEAT CAPACITY

  • Give the formula
A

C=q/∆T

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5
Q

What does a positive (+) ∆G mean?

A

Energy is available and the system CAN do work

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6
Q

If slow step is 1st step:

  • what can you do wrt the rate law?
A

the rate law can be written as if it were only 1 step

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6
Q

What 2 formulas relate:

  • Keq (equilibrium constant) to ΔG? (Gibbs Free energy )
A

∆G˚= - RTlnKeq

Keq=e-∆G/RT

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6
Q

The unit “Watt” is the same as?

A

Joules per second

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7
Q

What should you think of (and mentally replace!) whenever you see the word “TEMPERATURE?”

A

Temperature=

av. KE of molecules

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8
Q
  • 2 L container of water and 4 L container of water
    • Compare their heat capacities and SPECIFIC heat capacities
A

Heat capacity of 4L is twice as much as other

  • b/c theres more water available to absorb

Specific heat capacities are the same in both

  • because they’re both filled with water
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8
Q
  • Entropy (∆S) definition
    • units=?
A
  • a measure of disorder in a system
  • units=Joules/K
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9
Q

Do catalysts increase % yield?

A

NOPE!!

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9
Q

How is the sign of work determined in CHEMISTRY?

A
  • Work done ON system= positive
  • Work done BY system=Negative
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10
Q

∆Hvaporization definition

A
  • enthalpy value associated with phase change from liquid to gas
    • therefore, ∆Hcondensation is the same value, just with a reverse sign)
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11
Q

Chemistry definition for “Work”

A

a change in volume at a ~P

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12
Q

Catalyst definition

A

increases rxn rate w/o being consumed in the process

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12
Q

Elements in their elemental state have ∆H˚formation of?

A
  • ZERO
    • no ∆ in H needed to create THEMSELVES
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13
Q

Bond broken during rxn=energy ___

A

required

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15
Q

Writing rate laws: what must you assume? (2)

A
  1. assume rxns only proceed FORWARD
    • ​​ignore reverse rxn
  2. only consider the first few seconds of the rxn
    • at this time, theres a high [] of each reactant and catalysts (enzymes) present
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16
Q

Thermodynamics includes…(4)

A
  1. ΔG
  2. ΔH
  3. ΔS
  4. Keq
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17
Q
  • How will the following affect rxn rate?
    • ​increase [products]
A

NO EFFECT

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18
Q

When heat enters into a system, if the system is capable of volume change, heat can either…

A
  1. Do PV work
  2. Increase temperature (Av KE of molecules)

…or BOTH!!!!!

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19
Q

As far as the MCAT is concerned, ___ is the only thing that changes K

A

temperature

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20
Q

If, during a rxn, something happens and the Temp increases as a result, what must ∆H be?

A
  • (-)
    • aka exothermic
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21
Q

Calculating E˚ for electrochemical rxns

A
  • add together 1/2 rxns
    • but when calculating E˚, do NOT multiply by coefficients in balanced rxn
  • ​This is UNLIKE when you calculate ∆Hrxn by adding then multiplying BDE values by the coefficients
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21
Q

∆Hfusion definition

A
  • enthalpy value associated with phase change from liquid to solid
    • sign reverses for ∆Hmelting
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21
Q

As a rxn proceeds, if ∆S increases (becomes more disordered)….?

A
  • energy will be released
  • therefore more energy will be available to do work
  • in short: It’s FAVORABLE
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21
Q

Difference b/t spectator ion and catalyst

A
  • spectator ion
    • NO EFFECT
    • do NOT participate in rxn
  • catalyst
    • decreases Ea
      • ∴ increases rate
    • NOT consumed in rxn
      • makes it through the rxn without changing.
      • Same among products as it is among reactants
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22
Q
  • If a graph for a reactant is linear at:
    • ln[A] vs. time
    • slope=-k
    • …………it must be?
  • What if it isnt linear?
A
  • must be 1st order
  • not linear= not first order
  • ​​​could still be 0th or 2nd order
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23
Q

Don’t confuse standard state with?

A

STP values!

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24
Q

Large (-) ∆Hformation means what? (2)

A
  • Energy released when bonds are formed is very high
  • compound is VERY STABLE
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25
Q

What is a Black Body Radiator?

A
  • Theoretically perfect body that absorbs ALL energy that hits it
  • and then re-emits 100% of the energy absorbed
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26
Q

∆Hsolution definition

A

enthalpy value associated with dissolution of a species into a solution

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27
Q

Zeroth law of thermodynamics definition

A
  • If object A is in thermal equilib with object B,
  • nd obj. C is in thermal equilib with obj. B,
  • ​then obj. A and obj. C are **ALSO **in thermal equilibrium
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28
Q

What DO catalysts affect? What DONT they affect?

A
  • DO affect
    • rate (by lowering Ea)
  • DONT affect
    • Keq
    • ∆H
    • ∆S
    • ∆G
    • or any other thermodynamic properties
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29
Q

Define Conduction, give an exampleWhat thing is it similar to?

A
  • conduction=molecular collisions carry heat along a current
  • ex: pot of boiling watersimilar to current flow through a wire
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29
Q
  • ∆Hformation definition
    • Exothermic=?
    • Endothermic=?
A
  • enthalpy value for formation of a cpd from its elements in their natural state
  • Exothermic is **NEGATIVE **(-)
  • Endothermic is **POSITIVE **(+)
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30
Q

∆G (-) means?

A

energy must be added to rxn (i.e. heat must be added to system) to make it proceed

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31
Q

Define heat capacity

A

amount of energy (in joules or calories) a system must absorb to give a unit change in temperature

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32
Q

[OH][H]What increases in [] when you INCREASE pH?

A

[OH]

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34
Q

Give an example of ~V heat capacity

A

system confined by rigid walls

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35
Q

Second law of thermodynamics definition

A

heat cannot be changed COMPLETELY into work in a cyclical process, and ∆S in an isolated system can never decrease

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36
Q

Higher ∆S=more likely to…

A

happen spontaneously

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36
Q

What thermodynamic properties are”SPONTANEOUS?” or “FAVORABLE?”

A

∆G is (-)∆S is (+)∆H is (-)

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38
Q

Differentiate heat capacity “C” and specific heat capacity “c”

A

Heat capacity is for a system (ex: solution, container holding sol’n, etc.)Specific heat capacity describes energy absorption for ONE individual substance ONLY!

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39
Q

Think of “rate” as…(3 parts)

A
  1. a function of how fast the reactant molecules are moving,
  2. how much KE they have
  3. height of Ea “hill” that must be overcome to form products
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39
Q

Isothermal definition

A

~T (~av. KE of molecules)aka NO HEAT EXCHANGE

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40
Q

Name the 2 kinds of calorimeters and their distinguishable properties

A

1) Coffee cup (~P)2) Bomb (~V)

41
Q

As a rxn proceeds, if ∆S decreases…?

A

energy is REQUIRED to create the increased orderliness, and there’ll be exactly that much LESS energy available to do workin short: it’s UNFAVORABLE

41
Q

High (+) BDE means the cpd is very ___

A

stable

42
Q

If Keq > 1, rxn will be…?(if we are starting at standard conditions)

A

SPONTANEOUS!

43
Q

(+) ∆S=?

A

increased randomness, more energy available to do work

45
Q

How to calculate ORDER of each reactant (using experimental data)

A

1) Find 2 steps where [reac] in question changed, but ALL OTHERS DID NOT2) Note the factor by which [reac] changed3) note the factor by which RATE changed across those same 2 trials4) Use this to figure out X^Y=Z

46
Q

Think of ∆H as…units?

A

energy contained w/in chemical bondsunit= Joules

46
Q

When comparing trials to write a rate law for a reactant, what should you look for?

A

Find 2 trials where []’s of reactant A changes, but everything else (like [] of reactant B and temperature) stays the same. Something with the same conditions!

47
Q
  • How will the following affect rxn rate?
    • increasing energy of transition state
A
  • decrease rate
    • because it INCREASES Ea
48
Q

if slow step is 2nd, what happens wrt the rate law?

A

rate law=rate law of the slow stepslow step will include an intermediate as of the reactants

48
Q

∆G=-RTlnKeqWhat do you need to remember about this formula?

A

This formula helps find sign of ∆Gremember: ln of a (+) that is 1 is positive**remember the (-) sign in front of RT! If (lnKeq) is positive, that will turn it negative. Negative x positive=negative, therefore ∆G will be (-), & vice versa

50
Q

Definition of kinetics. How is it measured?

A
  • study of reaction RATE
  • measured in terms of how fast reactants DISAPPEAR, by tracking changes in [] of reactants
51
Q

If 2 objects are in thermal equilibrium, by definition they have what?

A

The SAME TEMP!

53
Q
  • How will the following affect rxn rate?
    • increase [reactants]
A

increase rate

55
Q

PV Work formulaWhat do you need for in order to see PV work, and what is a dead giveaway PV work has been done?

A

PV Work =P∆VNeeds ~P And change in Volume is a dead giveaway

56
Q

How will the following affect rxn rate? increasing energy of reactants

A

increase rate (increasing energy of reactants brings it closer to the Ea–easier to get over the “hill”)

57
Q

Define convectionWhat are 2 examples?

A

hotter sections of fluid rise, cooler portions sinkEX:Air currents & Convection currents (El Nino)

58
Q

The ln of and positive (+) numer LESS than 1 is?

A

negative (-)

59
Q

For a reaction to occur, what has to happen with regards to collisions?

A
  1. Reacs must collide with enough energy to overcome the Ea “hill”
  2. Reacs must be in correct spatial orientation
60
Q

What does Keq=1 mean?

A

rxn is at equilibrium∆G˚=0

61
Q

How to write rate law for a catalyzed rxn

A

write rate law in same way as normal, w/ [catalyst] added in as a reactant

61
Q

Define the first law of thermodynamics

A

Energy can’t be created nor destroyed

62
Q

Bomb calorimeter-how to solve-(What DOES and DOESNT it give?)

A

-solve using q=mc∆T-DOES give change in internal energy (∆U or ∆E) -DOESNT give negative ∆Hbomb calorimeter is at ~V, in a sealed steel container

64
Q

Which type of calorimeter allows for pv work? Why?

A

Coffee cup, because it’s at ~P

65
Q

What do you do to find the “overall order” of a rxn?

A

Add together the exponents in the rate law

66
Q

“Standard State” definition

A

a set of conditions set as a REFERENCE POINT for measuring ∆H, ∆G, and ∆S

67
Q

More unstable cpds: -∆Hcombustion?

A

have a HIGHER ∆Hcombustion, release MORE energy when reacted with O2

68
Q

Slow step=?

A

rate-determining step

69
Q

Third law of thermodynamics definition

A

pure crystalline substances at absolute zero have a ∆S of 0

71
Q

What are the 3 types of heat exchange?

A

1) Convection2) Radiation3) Conduction

73
Q

For ∆H rxn, if you’re given an ∆H value of +1.5, but your water is a reactant instead of a product, what do you do?

A

Reverse the sign to (-)

74
Q

Rate Order graphs: Second order

A

1/[A] vs time is linear, slope = k

75
Q

If a graph for a reactant is linear at:[A] vs. time, slope=-kit must be? What if it isnt linear?

A

Zeroth order not linear=not zeroth order, but it could be first or second, etc

76
Q

in a 2-step rxn, does the yield of the first rxn affect the Keq of the second?

A

NOPERS

77
Q

Specific heat capacity definition

A

describes energy absorption for ONE individual substance

78
Q

What do exponents in a rate law represent?

A

the “order” of each reactant

79
Q

If Keq < 1, rxn will be?

A

NON-spontaneous∆G˚ is (-)

80
Q

When calculating ∆Hrxn, what do you need to remember with regards to signs?

A

bonds FORMED= energy released (-)bonds BROKEN= energy req’d (+)

81
Q

Entropy increases with increasing…

A

number of moleculestemperaturevolumemoles of gas

83
Q

is heat capacity greater for ~V or ~P?

A

For ~P, because it CAN do pv work as well as temperature work (therefore has more “capacity” that a system with ~V)

84
Q

∆E=?

A

q+W

85
Q

What is a calorimeter?What do we assume about “q?”

A

a device used to calculate ∆Hassume q = ∆H, which is true at ~P

86
Q

Bond formed as result of rxn=energy ___

A

released

87
Q

Physics definition for “work”

A

energy transfer via a force

88
Q

Relationship b/t enzymes & catalysts

A

Enzyme=biological catalystALL enzymes are catalysts, but not all catalysts are enzymes

89
Q

What should you remember for the MCAT about thermal equilibrium?

A

Everything TENDS TO move towards thermal equilibrium with everything else. -objects with higher temperatures will always equilibrate over time with their surroundings, including other objects with which they are in contact

90
Q

When a solute is mixed in solution, ∆S is always ___. Why?

A

is always (+)something becomes more disordered dissolved in a solution

92
Q

∆Hcombustion definitionHigh ∆Hcombustion means what?

A

enthalpy value for combustion of a cpd w/ O2 to form water and CO2High ∆Hcomb. value=UNSTABLE molecule(low ∆Hcomb.value=stable)

94
Q

Rate Law equation:X^Y=Z What do X, Y, and Z represent?

A

X=factor by which [reac] changedY=order of reactantZ=factor by which the rate changed (across the same 2 trials)

95
Q

Anything to the zeroth power is equal to?

A

1

96
Q

∆Hrxn definitionHow do you solve for it? (1 step, 2 things to remember to do)

A

enthalpy change for a rxn. -Add together enthalpy change values from the table (given) that, when added, produce net rxn for which you are calculating ∆Hrxn-REMEMBER: if rxn proceeds in opposite direction as it would in the net rxn, change its sign! -REMEMBER: You need to multiply the value given in the table by the coefficient in the balanced net rxn (like…if ∆H value from table for H20 is 1.5 but you have 2 moles of water, multiply 1.5 x 2=3)

97
Q

Which thermodynamic elements are “NON-SPONTANEOUS” or “UNFAVORABLE?”

A

∆G is (+)∆S is (-)∆H is (+)

99
Q

(-) ∆S=?

A

less randomness, less energy available to do work

100
Q

Rate Order Graphs:Will only be linear when? (2)

A

1) When rxn only has 1 reactant, or2) when it is part of a multiple reactant rxn where rate is independent of ALL other reactants (basically, when the other reactant is zeroth order or is in excess)

101
Q
  • How will the following affect rxn rate?
    • increasing [catalyst]
A

**INCREASE **rate

102
Q

the word “decomposition” tells us what?

A

we are going from ONE species to 2+ species (∆S is positive)

103
Q

Thermodynamic Formula

A

∆G=∆H-T∆S

104
Q

Calculating ∆Hrxn using BDE’s

A

add up BDE’s in products & reactants-bond broken during rxn= energy REQUIRED, BDE has (+) sign-bond formed as a result of rxn= energy RELEASED, BDE has a (-) sign

105
Q

How is the sign (+/-) defined in PHYSICS?

A

When force & displacement are in same direction (ie lifting a box), work is (+)When force & displacement are in opposite direction (ie lowering a box), work is (-)

107
Q

Think of Gibbs Free Energy, ∆G, as…

A

the amount of “free” or “useful” energy available to do work (**Note**doesnt include pv work)

108
Q

How will the following affect rxn rate? increase temp

A

increases rate

109
Q

Give an example of ~P heat capacity

A

water in a beaker (open to the atmosphere)

110
Q

1˚ C= ___ Kelvin

A

274 K

111
Q

When is heat ,q, added exactly proportional to the increase in temperature? Why?

A

When system is at ~VNo PV work gets done–it 100% of energy added goes towards increasing temperature

112
Q

When values are given for standard state conditions, what thingy is added?

A

superscript is added –> ∆H˚ “not”

113
Q

Collisions cause?

A

reactions!

114
Q

Light colors radiate and absorb ___dark colors radiate and absorb ___

A

Light: absorb lessDark: absorb more

115
Q

Rate Order graphs: Zeroth order

A

[A] vs time is linear with slope= -k

116
Q

What are 2 ways to define the first law of thermodynamics?

A

1) total energy of an isolated system is constant2) Total energy in a closed system (energy can leave, mass can’t) is equal to the heat,q, absorbed by that system PLUS and work done on that system by its surroundings

117
Q

Isobaric definition

A

~P

118
Q

∆S increases with? (4, plus 1 caveat)

A

1) increased # of items/particles/molecules**CAVEAT: # moles gas trumps # moles in other phases (cause gas is VERY disordered)…2 mol react with 1 mol (g) product=Positive ∆S2) Increased Volume3) Increased temp (av. KE of molecules)4) Increased DISORDER (ex: amorphous struc more disordered than crystalline) and COMPLEXITY (ex: C2H6 has greated ∆S than CH4)

120
Q
  • How will the following affect rxn rate?
    • increase Ea
A

**DECREASE **rate

121
Q

If a graph for a reactant is linear at:1/[A] vs time, slope=-kit must be? what if it isnt linear?

A

it must be 2nd ordernot linear=not 2nd order. could still be 1st or 0th

122
Q

Rate Order graphs: first order

A

ln [A] vs time is linear with slope= -k

ALTIUS (27 decks)

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