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PHRM 513 > Thermodynamics > Flashcards

Thermodynamics Flashcards

1
Q

Thermodynamics

A

the study of energy and its transformations

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2
Q

Energy

A

the capacity to do work or transfer heat

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3
Q

work

A

the movement of an object abasing some force; force is a push or pull exerted on an object

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4
Q

heat

A

flow of energy from a body at higher temp. to one at a lower temp when they are placed in thermal contact

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5
Q

kinetic energy

A

the energy an object has due to its motion

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6
Q

potential energy

A

stored energy that results from the position

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7
Q

system

A

part of the universe we single out

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8
Q

surroundings

A

everything that exist outside the system

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9
Q

open system

A

can exchange both energy and matter with surroundings. ex chem Rxn in open flask

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10
Q

closed system

A

a system can exchange energy but not matter with surroundings. ex. chem rxn in stoppered flask

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11
Q

isolated system

A

can exchange neither matter nor energy with its surroundings. ex. sealed flask that is thermally, electrically, mechanically insulated

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12
Q

internal energy (U)

A

the sum of all kinetic and potential energy contribution

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13
Q

ΔU= w + q

A

equation for finding internal energy of a system. w=work q=heat

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14
Q

If w done onto system

A

w is greater than 0

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15
Q

If w done by system

A

w is smaller than 0

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16
Q

if q is absorbed from the surroundings, q>0 and the process is

A

endothermic

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17
Q

if q is released to the surroundings, q<0 then the process is

A

exothermic

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18
Q

When heat is added to a system or work is done on a system

A

its internal energy (U) increases

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19
Q

First law of thermodynamics

A

Energy can be transferred and transformed, but it cannot be created or destroyed.

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20
Q

Internal energy of an isolated system is

A

constant

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21
Q

3 examples of forms of energy

A

work, heat and light

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22
Q

Enthalpy (H)

A

related to the internal energy of a system plus the product of the pressure and volume of system
H= U + PV

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23
Q

Constant pressure w

A

-P∆V

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24
Q

when the reaction is not kept at a constant volume this equation is used for enthalpy

A

ΔH=ΔU + PΔV

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25
Q

When change in ΔH is positive, the process is

A

endothermic, it gained heat from the surroundings

26
Q

ΔH<0 the process is

A

exothermic, it released heat to the surroundings

27
Q

the process by which a drug particle dissolves is called

A

dissolution

28
Q

breaking solute-solute attractions is

A

endothermic

29
Q

breaking solvent-solvent attractions is

A

endothermic

30
Q

forming solute-solvent attractions is

A

exothermic

31
Q

Enthalpy change

A

sum of endothermic and exothermic interactions

32
Q

spontaneous processes

A
  • occur without outside assistance
  • occurs in a definite direction
  • they are spontaneous in one direction and non spontaneous in the reverse
33
Q

NaOH dissolving in water

A
  • Heat is liberated (exothermic)

- ∆H is negative

34
Q

NaNO3 dissolving in water

A
  • Solution becomes cooler
  • Heat is absorbed ( endothermic)
  • ∆H is positive
35
Q

reversible process

A

a system can be completely restored to its original condition with no net change to system or surroundings

36
Q

irreversible process

A

can’t be reversed to restore the system and surroundings to original state. all real processes that occur on their own are irreversible

37
Q

spontaneous processes are

A

irreversible: even if the system is restored to the original condition, the surroundings will have changed

38
Q

Entropy

A

measurement of randomness or disorder

- when a system becomes more chaotic, its entropy increases

39
Q

Second law of thermodynamics

A

any irreversible process results in an increase in entropy

40
Q

Primary reason for Micelle formation

A
  • attainment of a state of minimum free energy

- ex of thermodynamics

41
Q

Surface tension

A
  • force per unit length that must be applied parallel to the surface as to counterbalance the net inward pull
42
Q

Contraction

A

is spontaneous and the contracted surface represents a minimum free energy state

43
Q

Surfactants are

A
  • amphiphilic molecules ( have hydrophobic and hydrophilic parts)
  • orient themselves at the surface to remove the hydrophobic group from the aqueous environment
44
Q

Micelles form when

A

the surface layer is saturated with surfactant molecules and no further decrease in surface tension is possible

45
Q

which is most important in determining the free energy change

A

entropy

- in solution, hydrophobic molecules are surrounded by structured water

46
Q

What results in an increase in entropy

A
  • loss of ordered structure of the water molecules when the hydrophobic regions of the surfactant are removed
47
Q

Third Law of Thermodynamics

A
  • entropy of a perfectly organized crystal at absolute zero is zero
48
Q

In any dissolution, the entropy of a system

A

increases

49
Q

Gibbs free energy equation

A

ΔG = ΔH - TΔS

50
Q

Total entropy change

A

∆Stotal= ∆S+∆Ssurroundings

51
Q

For a spontaneous change, S is

A

positive, >0

52
Q

At constant Temperature and pressure, if ΔG>0 (positive) the reaction is

A

non spontaneous in the forward direction but spontaneous in the reverse rxn

53
Q

At constant Temperature and pressure, if ΔG<0 (negative) the reaction is

A

spontaneous in the forward reaction

54
Q

At constant Temperature and pressure, if ΔG=0 the reaction is

A

at equilibrium

55
Q

Equilibrium expression. K=

A

[C]^c[D]^d / [A]^a[B]^b

56
Q

If K and lnK <0 (negative), then ∆G is

A

positive

57
Q

If K and lnK >0 (positive), then ∆G is

A

negative

58
Q

If K and lnK =0, then ∆G is

A

=0

59
Q

The more negative ∆G,

A

the larger the equilibrium constant

60
Q

Oth Law

A

If two systems are at the same time in thermal equilibrium with a third, then all three are in thermal equilibrium

PHRM 513 (13 decks)

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