Simple Mixtures 2

Question 1

Mixture of benzene and toluene obeys ____ because ____ and

Answer 1

Raoult’s Law because it behaves ideally and there is no interaction between the two components

Partial pressures of both components are proportional to their respective mole fractions in liquid phase

Question 2

Partial pressures in a binary components are ___ to their respective ___ in the ____ phase

Answer 2

proportional
mole fractions
liquid

Question 3

In a binary mixture, the total pressure is the ____ of the ____ of both components

Answer 3

sum
partial pressures

Question 4

P benzene * ____ P toluene *

Answer 4

>

Question 5

Pressure-composition phase diagram is used to

Answer 5

describe binary mixtures at a given temperature if vapor pressure and composition of either liquid or vapor phase is known

Question 6

The variance (F) at liquid only and vapor only region

Answer 6

3: (P,x) or (P,y) T

Question 7

Variance (F) at liquid + vapor region

Answer 7

2: T, and P or x or y

Question 8

What will be the phase change if pressure is decreased?

Answer 8

From liquid only to liquid + vapor to vapor only

Question 9

If a point in l + v region is closer to liquid curve, n vapor ___ n liquid

Answer 9

<
the amount of liquid phase is greater than the amount of vapor phase

Question 10

Lever rule equation

Answer 10

(ol) (n liquid) = (ov) (n vapor)

Question 11

Example of binary system that deviates from ideality

Answer 11

acetone-carbon disulfide

Question 12

How acetone-CS2 system behave

Answer 12

As x CS2 approaches 1, Raoult’s Law is observed.

As x CS2 approaches 0, Henry’s Law is observed.

Behaves like an ideal dilute solution

Question 13

Henry’s Law vs Raoult’s Law

Answer 13

HL: Pj = Kj xj
RL: Pj = Pj* xj

Question 14

_____ solutions obey ideal dilute solution laws at the limit of ____ concentration

Answer 14

All; zero

Question 15

in a temperature-composition (LVE) liquid and vapor curves can be calculated via

Answer 15

Clausius-Clapeyron equation

Question 16

Describe the appearance of temperature-composition diagram (LVE)

Answer 16

Vapor is above the liquid curve. Both liquid and vapor curve are not straight line (curve). Initial temperature (bp) of toluene is higher than benzene.

Question 17

Temperature-composition diagram for ideal binary mixture is useful for?

Answer 17

fractional distillation of binary mixtures

Question 18

In fractional distillation, the binary mixture is ___ until ___ forms.

Answer 18

boiled until vapor forms

Question 19

In fractional distillation, the vapor formed is richer in the component that has ___ boiling point.

Answer 19

lower

Question 20

The condensed vapor, ____, is boiled again until it becomes ___ in the component that is more ___.

Answer 20

distillate; pure; volatile

Question 21

In fractional distillation, the more rounds of boiling-condensation, the ____

Answer 21

purer the distillate

Question 22

In fractionating columns, vapors rich in ___ volatile component (aka __) rise while vapor rich in ___ volatile component (aka __) collects at the bottom

Answer 22

more volatile; distillate
less volatile; residue

Question 23

The temperature in the top portion of fractioning column is ___ compared to that bottom portion

Answer 23

lower

Question 24

Clean separation between two components by fractional distillation is feasible only if?

Answer 24

there is significant difference in their boiling points

Question 25

Ethanol-water mixtures cannot be separated using fractional distillation because?

Answer 25

It is an azeotrope, do not behave ideally. Whatever vapor is formed, the composition is the same as that of the liquid

Question 26

The minimum point in the liquid curve that coincides with that of vapor curve implies?

Answer 26

at this temperature, the composition of liquid and vapor phase are identical.

Question 27

Why azeotrope deviate from ideality?

Answer 27

There is a significant interaction between the molecules of the two components.

Question 28

A ___ results if two liquids are fully miscible.

Answer 28

single phase

Question 29

A ___ system is observed when either component has limited solubility in the other.

Answer 29

biphasic system

Question 30

The region bounded by the curve is the ___ region under the critical temperature

Answer 30

biphasic region

Question 31

The lever rule is used to ___ in a LLE

Answer 31

determine the relative amount of phases present in the mixture

Question 32

If xa is closer to zero-mole fraction mark in butanol-water system, the amount of water-rich phase is ___ than the butanol-rich phase

Answer 32

greater

Question 33

(T/F) Binary mixtures can exhibit lower critical point, higher critical point, and both upper and lower critical point

Answer 33

True

Question 34

Melting point of solution ___ melting point of pure solvent

Answer 34

less than

Question 35

Point where the curves of two components will coincide.

Answer 35

eutectic point

Question 36

What happens at eutectic temperature?

Answer 36

mixture becomes fully solid regardless of its composition

Question 37

What happens at eutectic composition x E

Answer 37

mixture solidifies entirely without forming two separate liquid and solid phases

Question 38

Solid melt is not ___ and hence there are ___ phases

Answer 38

homogeneous; two distinct

Question 39

Equimolar mixture of liquid gallium and arsenic direct forms ___

Answer 39

solid gallium arsenide (GaAs)

Question 40

What will happen when other compositions of gallium and arsenide is used and not equimolar?

Answer 40

GaAs solidifies first, leaving the liquid mixture

Question 41

If there are excess arsenide in gallium-arsenide system, what solid will be formed and where?

Answer 41

solid GaAs and solid arsenide will be formed below the melting point of excess arsenide

Question 42

(T/F) Solid melt for equimolar mixture has two distinct phases

Answer 42

False. Only the compound is present, single phase

Question 43

(T/F) Binary system can exhibit both formation of eutectic mixture and formation of compound

Answer 43

True

Question 44

Line passing through the point where hex3cyc will form

Answer 44

peritectic line

Question 45

What happens at peritectic line?

Answer 45

three phases are in equilibrium: liquid mixture, solid hex, solid compound hex3cyc

Question 46

hex3cyc undergoes ___

Answer 46

incongruent melting. it forms a liquid with composition xp and solid hex

Question 47

(T/F) Acetic acid has limited miscibility with water while ethyl acetate is miscible with both water and ethyl acetate.

Answer 47

False. Ethyl acetate: limited miscibility with water. Acetic acid: miscible for both

Question 48

Ternary diagram shows the ___

Answer 48

degree of miscibility of three components

Question 49

The vertices represents ___, line connecting vertices represents ____, and any point inside the triangle represents ____.

Answer 49

vertices: pure solvent line connecting: mixture of two components point inside: mixture of three components

Question 50

The sum of the mole fractions of all three components should be equal to ___

Answer 50

one

Question 51

The biphasic region in ternary diagram is enclosed with __

Answer 51

binodal curve

Question 52

Binodal curve is determined by

Answer 52

experimental analysis of phases that separate when varying amount of three components are mixed

Question 53

The line in binodial curve that connects the composition of aqueous and organic phase

Answer 53

tie line

Question 54

Point in binodal curve in which two layers that separate will have almost the same composition

Answer 54

plait point

Question 55

at low concentration, acetic acid is ___ in ethyl acetate than in water

Answer 55

more soluble