Physical Transformation

Question 1

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

Answer 1

multi-component; the same; phase

Question 2

Chemical potential is an ___ property

Answer 2

intensive

Question 3

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

Answer 3

single; different phases; pressure and temperature

Question 4

At constant pressure: dGm/dT = ?

Answer 4

dGm/dT = -Sm

Question 5

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

solid liquid gas

Answer 5

solid liquid gas
gas has steepest slope

Question 6

Intersection of solid and liquid curves in Gm vs T graph

Answer 6

Transition point: Melting Point

Question 7

Intersection of liquid and gas curves in Gm vs T graph

Answer 7

transition temp: boiling point

Question 8

Gm and stability relationship

Answer 8

Lower Gm, More stable

Question 9

Most stable below melting point, Tm

Answer 9

solid

Question 10

Most stable between Tm and Tb

Answer 10

liquid

Question 11

Most stable above boiling point Tb

Answer 11

gas

Question 12

At constant temperature, dGm/dP = ?

Answer 12

Vm

Question 13

Shift of solid and liquid curves when decreasing pressure is

Answer 13

small decrease

Question 14

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

Answer 14

MP: changes very little
BP: significant decrease

Question 15

____ pressure by applying vacuum ____ temperature need to ____ solvents

Answer 15

decreasing pressure
decreases temperature
evaporate solvent

Question 16

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

Answer 16

Triple Point

Question 17

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

Answer 17

True

Question 18

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

Answer 18

gas is more stable than solid

Question 19

solid to gas:
gas to solid:

Answer 19

sublimation
deposition

Question 20

shows the most stable phase at given temperature and pressure

Answer 20

phase diagram

Question 21

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

Answer 21

density of solid water is less than liquid water

Question 22

Clapeyron Equation and what it describes

Answer 22

∆Sm/∆Vm = dP/dT

describes transformation of substances from one phase to another

Question 23

For fusion, change in P = ?

Answer 23

∆P=(∆Hfusion / ∆Vfusion)(∆T/Tm*)

Tm* = ref transition temp

Question 24

Clausius-Clapeyron Equation

Answer 24

∆Sm/Vm, gas = dP/dT

Question 25

For vaporization and sublimation, the expression is?

Answer 25

ln P/P0 = - (∆Htransition/R)(1/T - 1/T0)

Question 26

Phase Rule by J.W Gibbs

Answer 26

measures the degree of freedom (variance) of a system

number of variables needed to describe the state of system

F = Componemt - Phases + 2

Question 27

____ Classification of Phase Transition

Answer 27

Ehrenfest

Question 28

Most common phase transition

Answer 28

First-order

Question 29

For first-order transitions, the first derivative plot of chemical potential against temperature (__vs__) is ___ at transition temperature

Answer 29

Sm vs T; discontinuous

Question 30

____ change in entropy for first order transition since___

Answer 30

abrupt; heat is required to break bonds during phase transition at transition temperature

Question 31

discontinuity appear at ____ of chemical potential vs temperature (____)

Answer 31

second derivative
Cp, m vs T

Question 32

Second order transitions is common for

Answer 32

superconducting metals

Question 33

___ change in entropy for second order transition since ___

Answer 33

no change
no bond breaking occur, only change in molecular symmetry

Question 34

The ___ plot is lambda shaped

Answer 34

Cp,m vs T
second derivative of chem pot vs T

Question 35

Lambda transitions are for ___

Answer 35

paramagnetic- ferromagnetic transitions

Question 36

molecular transformation occurs ___ rather than abruptly in lambda transition

Answer 36

gradually

Question 37

(T/F): heating absorbs KE before transition point

Answer 37

False; heating increases KE before transition point

Question 38

at transition point, heat is ____ to ___

Answer 38

absorbed to break IMF between molecules

Question 39

at transition point, there is ___ in temperature and KE

Answer 39

no increase

Question 40

Heat capacity is in ____ at transition point

Answer 40

infinity

Question 41

When will temperature increases again after transition point?

Answer 41

When additional input of energy once transition from one phase to another is complete

Question 42

heat absorbed during transition

Answer 42

latent heat or enthalpy of transition

Question 43

(T/F): latent heat increases with KE

Answer 43

False. It increases PE of substance

Question 44

Why iodine does not really sublimes at ambient pressure?

Answer 44

Sublimation can only occur at 0.12 atm based on phase diagram

It will go from solid to liquid before liquid to gas

Question 45

Why iodine emits vapor at ambient pressure?

Answer 45

iodine has low vapor pressure
vapors are highly colored that even small amounts can be visible