Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

7.01 A Level Organic MH > 3.16 - Chromatography > Flashcards

3.16 - Chromatography Flashcards

1
Q

If the Stationary Phase is a Liquid, Separation occurs by ____ ?

A

Relative Solubility

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Uses of GC (Gas Chromatography)?

A

Separate Components - particularly volatile ones

low boiling points

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Stationary Phase: GC (Gas Chromatography)?

A

Solid or Solid coated with Liquid packed into a capillary tube

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Limitations of GC (Gas Chromatography)?

A

|> Many similar compounds have the same Retention time
|> Peaks of higher concentrations can hide peaks of lower concentrations
|> Unknown compounds have no Reference values

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Stationary Phase: CC (Column Chromatography)?

A

Solid packed in a glass column

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Properties that affect Strength of Adsorption & Relative Solubility?

A

Charge
Polarity
Chirality
Size

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Mobile Phase: CC (Column Chromatography)?

A

Liquid solvent (eluent) moves down the column

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Uses of TLC (Thin Layer Chromatography)?

A

Check Purity of Compounds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Stages of GC-MS

A

|> GC is first used to separate components in the mixture

|> Each separated component is directed to the mass spectrometer in turn

|> Each mass spectrum can be analysed or compared with a spectral database

|> Each component can be identified

|> Quantity of each component can be determined

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Stages of GC (Gas Chromatography)?

A

|> Mixture is injected into Gas chromatograph where it vapourises

|> Carrier gas flushes mixture through the column

|> Components slow down as they interact with the stationary phase

|> Each component leaves the column at a different time & is detected

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Stages of CC (Column Chromatography)?

A

|> Fill a Glass tube w/ stationary phase, held by a filter or mineral wool plug

|> Cover all powder in solvent

|> Dissolve the mixture to be sampled in minimum amount of solvent

|> Place mixture on top of solid phase

|> Run mixture through column by opening tap & adding solvent

|> Time taken for each component to reach end of column is recorded = retention time

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Stages of TLC (Thin Layer Chromatography)?

A

|> Dissolve small sample of mixture in solvent

|> Draw pencil line @ bottom of TLC plate

|> Place small spot of sample on pencil line, allow to dry

|> Place TLC plate in a beaker containing small amount of solvent - below pencil line

|> Cover with a lid

|> Allow solvent to rise

|> Once solvent has risen almost to top of plate, remove & mark solvent front

|> Use a locating agent to make compounds visible

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Mass Spectrometry is used to ____ the separated components by ____ ?

A

Identify

Comparing Mass spectra to a Database

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Examples of Locating Agents?

A

|> Ninhydrin
|> UV Light
|> I₂
|> KMnO₄

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Why is a Locating Agent useful for TLC (Thin Layer Chromatography)?

A

Make Compounds Visible)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Advantages of CC (Column Chromatography)?

A

Fairly large amounts can be separated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Advantages of TLC (Thin Layer Chromatography) compared to Paper Chromatography?

A

|> Better Resolution
|> Faster
|> Smaller amounts of Samples needed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Mobile Phase: GC (Gas Chromatography)?

A

Unreactive Gas passes through column @ high pressure & high temp

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

If the Stationary Phase is a Solid, Separation occurs by ____ ?

A

Adsorption

20
Q

The Stronger the Adsorption to the Stationary ____ phase the ____ the component moves through the ____ phase?

A

Solid
Slower
Mobile

21
Q

What is a Mass Spectrum?

A

Plot of Relative Abundance against Mass to Charge Ratio (m/z)

22
Q

In a Mass Spectrum, Peak with Highest m/z is due to the ____ ?

A

Molecular ion
M⁺ Peak
Gives Mr

23
Q

Limitations of TLC (Thin Layer Chromatography)?

A

|> Unknown compounds have no Rf values for reference

|> Similar compounds have similar Rf values

|> Can be difficult to find a solvent that gives good separation

24
Q

Define: Rf

A

Rf = Distance moved by spot/Distance moved by solvent

25
Q

Uses of CC (Column Chromatography)?

A

Separate & Collect larger quantities of compounds of a mixture

26
Q

Why must the Solvent be Below the Pencil line in TLC (Thin Layer Chromatography)?

A

Prevent samples Dissolving into Solvent

27
Q

The Greater the Solubility in the Stationary ____ phase, the ____ the component moves through the ____ phase?

A

Liquid
Slower
Mobile

28
Q

Define: Adsorption

A

Process by which a solid holds molecules to its surface

29
Q

Define: Retention time

A

Time taken for each component to reach the end of the column from injection to detection

30
Q

What can Chromatography be used for?

A

Separating & Identifying components in a mixture

31
Q

Two Phases of Chromatography?

A

Moving Phase

Stationary Phase

32
Q

Define: Phase

A

A state,

such as a Solid, Liquid or Gas

33
Q

Stationary Phase: TLC (Thin Layer Chromatography)

A

Solid on a Glass Support

34
Q

Mobile Phase: TLC (Thin Layer Chromatography?

A

Liquid Solvent which moves vertically up the plate

35
Q

What does separation depend on?

A

Balance between Solubility in Moving Phase
&
Retention in the Stationary Phase

36
Q

Uses of GC-MS?

A

|> Forensic & Drug Analysis
|> Environmental Sampling
|> Airport Security - Drugs & Explosives
|> Space Probes

37
Q

What does the No. of Peaks of a Gas Chromatograph represent?

A

Number of Components in the mixture

38
Q

The Rate of Movement of a Component is recorded as ____ ?

A

an Rf value
or
a Retention time

39
Q

What can Rf values or Retention times be used for?

A

Identifying a Compound

40
Q

Why does TLC (Thin Layer Chromatography) require a Lid?

A

Avoid Evaporation of Solvents

41
Q

What is the Area under each Peak of a Gas Chromatograph proportional to?

A

The amount of a component in the mixture

42
Q

Gas Chromatography can be combined with ____ to improve identification?

A

Mass Spectrometry

43
Q

Gas Chromatography is used to ____ components but is not good @ ____ ?

A

Separate

Identifying

44
Q

What is the Solvent Front?

A

Distance travelled up Plate by Solvent

45
Q

Why must a Pencil be used on TLC (Thin Layer Chromatography) plates?

A

Pen would dissolve into solvent & affect result

7.01 A Level Organic MH (18 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions