Physical Transformation Flashcards

1
Q

For a __ system to be at equilibrium, the chemical potential of each component should be ___ throughout the system, regardless of the ___ it is in.

A

multi-component; the same; phase

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2
Q

Chemical potential is an ___ property

A

intensive

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3
Q

If there is only __ component in a system, it can exist in ____ depending on the ___ and ___

A

single; different phases; pressure and temperature

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4
Q

At constant pressure: dGm/dT = ?

A

dGm/dT = -Sm

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5
Q

Arrange in increasing entropy (steepest slope dGm/dT):

solid liquid gas

A

solid liquid gas
gas has steepest slope

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6
Q

Intersection of solid and liquid curves in Gm vs T graph

A

Transition point: Melting Point

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7
Q

Intersection of liquid and gas curves in Gm vs T graph

A

transition temp: boiling point

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8
Q

Gm and stability relationship

A

Lower Gm, More stable

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9
Q

Most stable below melting point, Tm

A

solid

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10
Q

Most stable between Tm and Tb

A

liquid

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11
Q

Most stable above boiling point Tb

A

gas

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12
Q

At constant temperature, dGm/dP = ?

A

Vm

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13
Q

Shift of solid and liquid curves when decreasing pressure is

A

small decrease

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14
Q

Melting point ___ while boiling point ___ when pressure is decreased.

A

MP: changes very little
BP: significant decrease

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15
Q

____ pressure by applying vacuum ____ temperature need to ____ solvents

A

decreasing pressure
decreases temperature
evaporate solvent

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16
Q

Pressure and temperature at which all solid, liquid, and gas curves intersect

A

Triple Point

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17
Q

(T/F): Triple point is a characteristic of a substance

A

True

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18
Q

For select substances, there exists a pressure at which the gas curve is shifted in such way that at certain temperature, …

A

gas is more stable than solid

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19
Q

solid to gas:
gas to solid:

A

sublimation
deposition

20
Q

shows the most stable phase at given temperature and pressure

A

phase diagram

21
Q

Why solid-liquid curve of water slants to the left?

A

density of solid water is less than liquid water

22
Q

Clapeyron Equation and what it describes

A

∆Sm/∆Vm = dP/dT

describes transformation of substances from one phase to another

23
Q

For fusion, change in P = ?

A

∆P=(∆Hfusion / ∆Vfusion)(∆T/Tm*)

Tm* = ref transition temp

24
Q

Clausius-Clapeyron Equation

A

∆Sm/Vm, gas = dP/dT

25
For vaporization and sublimation, the expression is?
ln P/P0 = - (∆Htransition/R)(1/T - 1/T0)
26
Phase Rule by J.W Gibbs
measures the degree of freedom (variance) of a system number of variables needed to describe the state of system F = Componemt - Phases + 2
27
____ Classification of Phase Transition
Ehrenfest
28
Most common phase transition
First-order
29
For first-order transitions, the first derivative plot of chemical potential against temperature (__vs__) is ___ at transition temperature
Sm vs T; discontinuous
30
____ change in entropy for first order transition since___
abrupt; heat is required to break bonds during phase transition at transition temperature
31
discontinuity appear at ____ of chemical potential vs temperature (____)
second derivative Cp, m vs T
32
Second order transitions is common for
superconducting metals
33
___ change in entropy for second order transition since ___
no change no bond breaking occur, only change in molecular symmetry
34
The ___ plot is lambda shaped
Cp,m vs T second derivative of chem pot vs T
35
Lambda transitions are for ___
paramagnetic- ferromagnetic transitions
36
molecular transformation occurs ___ rather than abruptly in lambda transition
gradually
37
(T/F): heating absorbs KE before transition point
False; heating increases KE before transition point
38
at transition point, heat is ____ to ___
absorbed to break IMF between molecules
39
at transition point, there is ___ in temperature and KE
no increase
40
Heat capacity is in ____ at transition point
infinity
41
When will temperature increases again after transition point?
When additional input of energy once transition from one phase to another is complete
42
heat absorbed during transition
latent heat or enthalpy of transition
43
(T/F): latent heat increases with KE
False. It increases PE of substance
44
Why iodine does not really sublimes at ambient pressure?
Sublimation can only occur at 0.12 atm based on phase diagram It will go from solid to liquid before liquid to gas
45
Why iodine emits vapor at ambient pressure?
iodine has low vapor pressure vapors are highly colored that even small amounts can be visible