Separations and Purifications

Question 1

adsorption: how well a component of the mixture ____ to the ____ phase

Answer 1

sticks, stationary

Question 2

solubility: how well a component of the mixture ____ in the ____ phase

Answer 2

dissolves, mobile

Question 3

the higher the adsorption to the stationary phase, the ___ the molecule will move through the column

Answer 3

slower

Question 4

the higher the solubility in the mobile phase, the ____ the molecule will move through the column

Answer 4

faster

Question 5

The ____ of a component is the distance travelled by the component over the distances traveled by the solvent (mobile phase)

Answer 5

retention factor

Question 6

thin layer chromatography: stationary phase = _____, mobile phase = _______; non-polar compounds are ____ (___Rf) while polar-compounds are _____ (___ Rf).

Answer 6

stationary phase = glass plate coated in absorbent material (silica or alumina)
Mobile phase = organic solvent
non polar = more soluble (higher Rf)
polar = more adsorbent (lower Rf)

Question 7

Column chromatography: silica acts as the ____ and the _____ (mobile phase) is then allowed to flow through the silica beads; the different components of the analyte exhibit varying degrees of ___ to the silica = travel at different speeds through ____ as the solvent flows through it

Answer 7

stationary phase, solvent, adhesion, the stationary phase

Question 8

Column chromatography: The components that adhere more strongly to the stationary phase travel ____ compared to those with a weaker adhesion

Answer 8

slower

Question 9

High-pressure liquid chromatography (HPLC): a more accurate version of column chromatography; HPLC uses a ___ to force the solvent through the column at high pressure; particularly useful for mixtures containing ____ which have a ____ resistance to the mobile phase flow.

Answer 9

pump, very small particles, higher

Question 10

Gas chromatography involves samples being ____ and passed through a liquid or solid ___ phase using a gaseous (nitrogen or argon) ____ phase; the molecules with the ____ BP come out of the column first; at the end of the stationary phase, there is a detector that works out ____ are found at different times.

Answer 10

vaporized, stationary, mobile, lowest, how many particles of each component

Question 11

Distillation is a purification method where the components of a liquid mixture are ___ and then ___ and ___ at different boiling point

Answer 11

vaporized, condensed, isolated

Question 12

Distillation is an effective method to separate mixtures comprised of _____

Answer 12

2 or more pure liquids

Question 13

In simple distillation, a mixture is heated and the most volatile component vaporizes (evaporates) ___, at the _____ temperature. The vapor passes through a cooled tube, where it condenses back into liquid state –> pure, condensed liquid that is collected is called the ____.

Answer 13

first, lowest, distillate

Question 14

Fractional Distillation is used when there is a more complex mixture often with many fractions with not just fixed ____ but ___ of temperature where they boil

Answer 14

boiling points, ranges

Question 15

Vacuum distillation uses a vacuum to ____ the boiling point of the components so lower temperatures can be used for more ____ substances

Answer 15

lower, volatile

Question 16

A phenomenon in which increased surface tension allows a liquid to exceed its boiling point without actually boiling

Answer 16

superheating

Question 17

If the tension is broken during superheating, ____ can occur. To prevent this, ___ are often added as a nucleation surface to encourage the formation of air bubbles during boiling.

Answer 17

violent flash boiling, boiling chips

Question 18

The aqueous phase contains _____

Answer 18

water and other charged ions and species

Question 19

the organic phase contains ____

Answer 19

neutral compounds in the organic solvent

Question 20

In oil and water mixture (immiscible liquids), the aqueous phase forms at the bottom because ____, and the oil layer form on the top since it has ____

Answer 20

water is denser, a lower density

Question 21

The more dense, top layer is often the ____

Answer 21

organic layer

Question 22

Extraction with a separating funnel is useful to separate reaction product mixtures where the desired product and the side products have ____

Answer 22

different solubilities

Question 23

Extraction is not an effective method to separate _____ because most are miscible with each other

Answer 23

two organic layers

Question 24

A racemic mixture is a _____ of _______

Answer 24

50:50 mixture of two enantiomers

Question 25

In a racemic mixture, each enantiomer rotates plane-polarized light in an equal but opposite direction (because they are ___ images) so the racemic mixture is optically ____.

Answer 25

mirror, inactive

Question 26

One method for resolving a racemic mixture is the reaction of that racemate with an enantiomerically-pure ___ --> produces a mixture of ____

Answer 26

chiral reagent, diastereomers

Question 27

enantiomers have ____ physical properties = makes them ___ to separate; diastereomers have ___ physical properties = __ to separate

Answer 27

identical, hard, different, easy

Question 28

___ can also be used to separate a racemic mixture, a ___ stationary phase that will only bind to the __ is used to isolate one of the confirmations

Answer 28

chromatography, chiral, R of S confirmation

Question 29

proteins in their natural, tertiary-structured states can be run on ____ gels, which separates proteins by both ____ and ____.

Answer 29

native-PAGE, size and conformation

Question 30

Proteins can be chemically denatured before running them on the gel = _____, in this case proteins are separated exclusively by ____.

Answer 30

SDS-Page, size

Question 31

Proteins can be further denatured by the addition of a reducing agent that breaks down the ____ bonds between ___ residues, these are not fully broken by SDS alone

Answer 31

disulfide, cysteine,

Question 32

Samples of proteins and peptides can also be separated by _____ chromatography, in which molecules in solution are separated by their _____

Answer 32

size-exclusion, molecular weight

Question 33

Size-exclusion chromatography: as the solution travels down the column some ___ particles get stuck in the pores, the ___ molecules simply pass by the pores because ___. ___ molecules flow through the column ____ than ____ molecules, so ____ molecules have longer retention times

Answer 33

small, large, they are too larger to enter the pores, larger, faster, smaller, smaller

Question 34

ion exchange chromatography is used to separate molecules (or proteins) according to their ___.

Answer 34

charge

Question 35

Ion exchange chromatography is based on the _____ between ___ charged ions

Answer 35

attraction, oppositely

Question 36

A cationic stationary phase is used to separate ____ in cation-exchange chromatography

Answer 36

ANIONS

Question 37

An anionic stationary phase is used to separate ___ in anion exchange chromatography

Answer 37

CATIONS

Question 38

Affinity purification of protein complexes involves a specific protein being manipulated to express an ___ tag. The tag serves as a tool to ___ the bait protein and associated proteins by ____ chromatography. This occurs when the ____ on the protein is attracted to a _____ antigen/nucleic acid in the chromatography process.

Answer 38

affinity, purify, affinity, affinity tag, highly specific

Question 39

Is used to identify and determine the composition of a molecule, an energy source causes the molecule to break into smaller fragments which are detected by their ___ ratio

Answer 39

Mass spectrometry, mass to charge ratio

Question 40

enables scientists to determine the 3-D structure of a protein crystal at atomic resolution by analyzing the patterns created by deflected X-rays

Answer 40

x-ray crystallography

Question 41

uses the magnetic properties of atoms to determine the composition and 3-D structure of proteins in solution.

Answer 41

Nuclear magnetic resonance (NMR)