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Physical Chemistry (lec) > Simple Mixtures 2 > Flashcards

Simple Mixtures 2 Flashcards

1
Q

Mixture of benzene and toluene obeys ____ because ____ and

A

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

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2
Q

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

A

proportional
mole fractions
liquid

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3
Q

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

A

sum
partial pressures

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4
Q

P benzene * ____ P toluene *

A

>

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5
Q

Pressure-composition phase diagram is used to

A

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

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6
Q

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

A

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

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7
Q

Variance (F) at liquid + vapor region

A

2: T, and P or x or y

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8
Q

What will be the phase change if pressure is decreased?

A

From liquid only to liquid + vapor to vapor only

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9
Q

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

A

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

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10
Q

Lever rule equation

A

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

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11
Q

Example of binary system that deviates from ideality

A

acetone-carbon disulfide

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12
Q

How acetone-CS2 system behave

A

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

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13
Q

Henry’s Law vs Raoult’s Law

A

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

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14
Q

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

A

All; zero

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15
Q

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

A

Clausius-Clapeyron equation

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16
Q

Describe the appearance of temperature-composition diagram (LVE)

A

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.

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17
Q

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

A

fractional distillation of binary mixtures

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18
Q

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

A

boiled until vapor forms

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19
Q

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

A

lower

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20
Q

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

A

distillate; pure; volatile

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21
Q

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

A

purer the distillate

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22
Q

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

A

more volatile; distillate
less volatile; residue

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23
Q

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

A

lower

24
Q

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

A

there is significant difference in their boiling points

25
Q

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

A

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

26
Q

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

A

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

27
Q

Why azeotrope deviate from ideality?

A

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

28
Q

A ___ results if two liquids are fully miscible.

A

single phase

29
Q

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

A

biphasic system

30
Q

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

A

biphasic region

31
Q

The lever rule is used to ___ in a LLE

A

determine the relative amount of phases present in the mixture

32
Q

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

A

greater

33
Q

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

A

True

34
Q

Melting point of solution ___ melting point of pure solvent

A

less than

35
Q

Point where the curves of two components will coincide.

A

eutectic point

36
Q

What happens at eutectic temperature?

A

mixture becomes fully solid regardless of its composition

37
Q

What happens at eutectic composition x E

A

mixture solidifies entirely without forming two separate liquid and solid phases

38
Q

Solid melt is not ___ and hence there are ___ phases

A

homogeneous; two distinct

39
Q

Equimolar mixture of liquid gallium and arsenic direct forms ___

A

solid gallium arsenide (GaAs)

40
Q

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

A

GaAs solidifies first, leaving the liquid mixture

41
Q

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

A

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

42
Q

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

A

False. Only the compound is present, single phase

43
Q

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

A

True

44
Q

Line passing through the point where hex3cyc will form

A

peritectic line

45
Q

What happens at peritectic line?

A

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

46
Q

hex3cyc undergoes ___

A

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

47
Q

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

A

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

48
Q

Ternary diagram shows the ___

A

degree of miscibility of three components

49
Q

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

A

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

50
Q

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

A

one

51
Q

The biphasic region in ternary diagram is enclosed with __

A

binodal curve

52
Q

Binodal curve is determined by

A

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

53
Q

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

A

tie line

54
Q

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

A

plait point

55
Q

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

A

more soluble

Physical Chemistry (lec) (4 decks)

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