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1101 > THERMODYNAMICS > Flashcards

THERMODYNAMICS Flashcards

1
Q

1st Law of Thermodynamics

A

Energy cannot be created or destroyed.

INTERNAL ENERGY of an ISOLATED system is CONSTANT.

ΔE = E(FINAL) – E(INITIAL)

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2
Q

EXOTHERMIC

____ enthalpy

A

Heat transfer TO surroundings

-ΔH
Bonds formed are STRONGER than broken.

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3
Q

ENDOTHERMIC

___ enthalpy

A

Reaction requires/absorbs heat

+ΔH
Bonds formed are WEAKER than broken.

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4
Q

OPEN SYSTEM

A

Exchanges matter & energy with surroundings

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5
Q

CLOSED system

A

Exchanges energy with the surroundings (not matter)

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6
Q

ISOLATED system

A

neither energy nor matter exchanged with surroundings

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7
Q

STATE functions

A

value depends only on present state of system, not path used to arrive

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8
Q

EXPANSION WORK equation

A

w = F x d

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9
Q

ENTHALPY (H)

ΔH =
ΔH =

A

Heat change during a reaction at constant pressure.

State function.

ΔH = H (products) – H (reactants)
ΔH = H (Bond BREAKING) - H (MAKING)
ΔH = ΔE + PΔV
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10
Q

Enthalpy of FUSION

A

Heat required to melt a substance without changing its temp.

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11
Q

Enthalpy of VAPORISATION

A

Heat required to vaporise a substance without changing temp.

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12
Q

Enthalpy of SUBLIMATION

A

Heat required to convert a substance from solid to gas directly.

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13
Q

CALORIMETRY

A

Measure HEAT FLOW at CONSTANT
(A) PRESSURE, ΔH.
(B) VOLUME, ΔE

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14
Q

Heat capacity (C)

A

Heat required to raise the temp. of a substance by a specific amount.

q = C x ΔT

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15
Q

Molar Heat Capacity (Cm)

A

Heat required to raise temp. of 1 mol of substance by 1 C.

q = Cm x mols x ΔT

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16
Q

Specific Heat Capacity

A

Heat required to raise the temp. pf 1g substance by 1 C.

q = C m ΔT

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17
Q

Hess’ Law

A

Overall ENTHALPY change is the sum of all the individual steps of the reaction.

ΔH = ΔH1 + ΔH2

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18
Q

Standard Enthalpy of Formation ΔH

A

Heat change when 1 mol of compound forms from its elements under standard conditions.

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19
Q

Standard enthalpy of formation of an element in its standard state =

A

0

= ΔH products - ΔH reactants

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20
Q

Bond dissociation energy

A

energy required to break a chemical bond of a molecule in its gaseous state & energy released when the bond forms.

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21
Q

Bond enthalpy values depend on

A

Bond order
Electronic environment of atoms comprising a bond.
IN GASEOUS PHASE

22
Q

Bond enthalpy =

A

Bond enthalpy = ΔH reactant - ΔH product bonds

23
Q

Standard enthalpy of Combustion

A

ΔH per mol of combustible substance.

24
Q

ΔH

A

Heat change in a reaction at constant pressure.

25
Q

ΔS

A

Amount of freedom of motion / randomness in a system.

State function

26
Q

SPONTANEOUS reaction:

_ΔH, _ΔS

A

-ΔH, +ΔS

27
Q

NON-SPONTANEOUS reaction:

_ΔH, _ΔS

A

+ΔH, -ΔS

28
Q

ΔS =

A

ΔS = S(FINAL) - S(INITIAL)

ΔS=q(rev)/T
= heat reversibly transfered to substance / temp. (ENTROPY OF HEATING WATER)

29
Q

2nd law of thermodynamics

A

entropy of the universe INCREASES in a spontaneous process.

30
Q

3rd law of thermodynamics

A

entropy of a perfectly ordered crystalline substance at 0K is ZERO.

ATOMS ARE STATIONARY at absolute zero
-> ZERO ENTROPY.

31
Q

ENTROPY is greatest in gases and less in solids.

T or F

A

T

32
Q

SPONTANEOUS PROCESS: ΔS(universe) =

EQUILIBRIUM: ΔS(universe) =

A 
ΔS(universe) = ΔS(sys) + ΔS(sur) > 0
ΔS(universe) = ΔS(sys) + ΔS(sur) = 0
33
Q

Standard molar entropy

A

entropy of 1 mol of pure substance at 1 atm & specified temp.

34
Q

Bond DISSOCIATION (breaking) is a ___thermic process

A

ENDO

35
Q

Bond ASSOCIATION (making) is a ___thermic process

A

EXO

36
Q

State the equation for bond enthalpies relating bond dissociation & association

A

ΔH = H (BOND BREAKING) – H (BOND MAKING)

37
Q

SPONTANEOUS process

_ΔH, _ΔS

A

-ΔH, +ΔS

38
Q

NON-SPONTANEOUS

_ΔH, _ΔS

A

+ΔH, -ΔS

39
Q

ENTROPY, S

A

Measure of freedom of motion / randomness / DISORDER in a system

40
Q

Compare the entropy of solid, liquid, and gaseous states

A

S(SOLID)

41
Q

Relate entropy and heat reversibly transferred to a substance.

A

ΔS = q REV / T

42
Q

SPONTANEOUS processes:

ΔS(UNIV) = ΔS(SYS) __ ΔS(SUR) __ 0

A

ΔS(UNIV) = ΔS(SYS) + ΔS(SUR) > 0

43
Q

EQUILIBRIUM processes:

ΔS(UNIV) = ΔS(SYS) __ ΔS(SUR) __ 0

A

ΔS(UNIV) = ΔS(SYS) + ΔS(SUR) = 0

44
Q

Standard molar entropy

A

entropy of 1 mol of pure substance at 1 atm pressure and a specified temp.

45
Q

Standard entropy of reaction

A

entropy change for a reaction at 1 atm and 25 C.

46
Q

RELATE G, H, T and S.

A

ΔG = ΔH – TΔS

47
Q

SPONTANEOUS
_ΔS
_ΔG

A

+ΔS

-ΔG

48
Q

NON-SPONTANEOUS:
_ΔS
_ΔG

A
  • ΔS

+ ΔG

49
Q

EQUILIBRIUM
_ΔS
_ΔG

A 
ΔS = 0
ΔG = 0
50
Q

What does IC50 measure

A

INHIBITOR POTENCY: inhibitor conc which reduces enzymatic activity by 50%.

51
Q

EXERGONIC

_ΔG

A

Reaction releases more energy than it consumes.

-ΔG

52
Q

ENDERGONIC

_ΔG

A

Reaction consumes more energy than it releases.

+ΔG

1101 (8 decks)

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