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DS1101 - S1 Y1 > Chemistry Pracs > Flashcards

Chemistry Pracs Flashcards

1
Q

What process is used for separating and identifying amino acids in a mixture based on their different chemical characteristics

A

Thin layer chromatography

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2
Q

What is thin layer chromatography

A

Where a mobile phase is able to move the component of the mixture that you are trying to separate and there is a stationary phase that the mobile phase moves over and it is interaction between the components of the mixture and the stationary phase that allows the mixture to be separated into the different pure compounds

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3
Q

What are the 3 steps to the thin layer chromatography technique

A
  1. Spotting
  2. Development
  3. Visualization
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4
Q

What substance was the reactant in TLC

A

Aspartame

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5
Q

What are the amino acids which make up aspartame

A
  • phenylalanine
  • aspartic acid
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6
Q

What are the 2 functional groups in amino acids and describe if they are acidic or basic

A

acidic carboxylic acid and basic amino group

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7
Q

What binds the mobile phase to the stationary phase

A

H-bonds

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8
Q

how do you explain the results from thin layer chromatography

A

The absorbent material is usually silica gel or alumina which contains polar functional groups which can form H-bonds with AA.
So if the AA is polar it will form strong intermolecular bonds and will not travel as high as an amino acid which is not polar.

You compare the distances travelled by the unknown amino acid to distances of known amino acids

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9
Q

What 2 factors affect the migration rate of an amino acid

A
  • solubility of the side chain in the solvent
  • Affinity of the amino acid for the stationary phase
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10
Q

Amino acids with similar side chains are supposed to what

A

move with similar though not identical migration rates

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11
Q

What are the dependent factors of thin chromatography

A
  • Distance travelled by the amino acid
  • Distance travelled by the solvent front
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12
Q

how does the solvent (mobile phase) move up the stationary phase

A

capillary action

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13
Q

What is the stationary phase mostly made up of

A

silica gel or alumina

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14
Q

What is the stationary phase in thin layer chromatography

A

the adsorbent material on the TLC plate

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15
Q

What is the solvent front

A

how far the solvent has traveled along the plate

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16
Q

What is the mobile phase of thin layer chromatography

A

The solvent (amino acid mixture)

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17
Q

How is the position of the amino acid visualized

A

Spraying the TLC plate with a ninhydrin solution

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18
Q

What does spraying the TLC plate with ninhydrin solution do

A

It reacts with the amino group of the amino acid causing it to turn purple (proline not having a primary amine gives a yellow colour)

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19
Q

What is the retention factor (Rf)

A

quantitative measure to describe the migration of a compound relative to the solvent from the TLC plate. Its the ratio of the distance travels by the amino acid and by the solvent front

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20
Q

What is the equation for the retention factor

A
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21
Q

Why is is aspartame hydrolyzed with HCl

A

breaks down aspartame into its amino acids

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22
Q

What is the function of HCl in the hydrolysis of aspartame

A

catalyst

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23
Q

what is the machine called which measures the absorbance of a chemical solution

A

spectrometer

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24
Q

This is lecithin

A

Choline

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25
Q

This is lecithin

A

Phosphate

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26
Q

This is lecithin

A

Glycerol

27
Q

This is lecithin

A

Hydrophobic tail

28
Q

This is lecithin

A

Hydrophilic head

29
Q

What is the term where a molecule is both hydrophobic and hydrophilic

A

amphipathic

30
Q

What is the cell membrane made of

A
  • glycerophospholipids
  • proteins
  • cholesterol
31
Q

What are factors which influence the integrity of lipid bilayer/ solution polarity (4)

A
  • Extreme temperatures (heat and cold)
  • Extreme pH
  • Alcohol
  • Detergent
32
Q

What is the main lipid which comprises the cell membrane

A

glycerophospholipids

33
Q

What describes the dynamic nature of a cell membrane

A

the fluid mosaic model

34
Q

What cell membrane is used in the experiment which test factors which influence cell membrane function and permeability

A

cell membrane of beetroot

35
Q

Why was the beetroot cell membrane chosen

A

Because changes to membrane fluidity and permeability can be identified quantitatively by the leaking of red-coloured pigments that normally resides inside the cell

36
Q

What is the name of the beetroot pigment

A

betanin (a class of betacyanins)

37
Q

What is the enzyme used in prac 3

A

a- amylase

38
Q

What is the function of a-amylase

A

an enzyme (globular protein) found in saliva that hydrolyses starch into glucose

39
Q

What are other enzymes found in saliva

A

lactoperoxidase and lysozyme which exhibit an antimicrobial role

40
Q

What is the blue-black colour a measure of in prac 3

A

the formation of a starch-iodine complex (presence of starch - the reaction has not occurred)

However if starch is hydrolyses it will become smaller sugars which don’t form this complex

41
Q

What are some factors which influence activity of enzymes

A

-temperature
- pH

42
Q

What is oxidation

A

the loss of electrons by a substance, which is said to be oxidised in the process

43
Q

What is reduction

A

the gain of electrons by a substance which is said to be reduced in the process

44
Q

What is an oxidation-reduction reaction

A

In an oxidation-reduction reaction, electrons re transferred from one species to another, and the valence states or oxidation state of elements are changed in the process.

45
Q

What are the components of a galvanic cell

A
  • 2 electrodes known as cathode and anode
  • solutions in which the electrodes are immersed in
  • salt bridge (non-reacting ions that connect the half cells and maintain charge balance)
  • Conductor (to transfer the electrons from one electrode to another)
46
Q

What is the function of a salt bridge in a galvanic cell

A

It allows ions to travel between the containers to maintain electrical neutrality as negatively charged electrons are moved from one side to the other

47
Q

What are electrodes

A

the 2 solid metals that are connected by the external circuit

48
Q

What is an anode

A

The electrode where oxidation occurs, this is where electrons are released.
Negatively charged since electrons are negatively charged

49
Q

What is a cathode

A

the electrode where reduction occurs. Positively charged since because it appears to attract the negative electrons

50
Q

What direction does electrons flow in a galvanic cellf

A

from anode to the cathode

51
Q

What is the name of the equation which calculates emf

A

Nernst Equation

52
Q

What is the equation for Ecell

A

Ecell = Ecathode - Eanode

53
Q

What does a positive emf indicate

A

that reduction occurs on the right in the diagram

54
Q

What does a negative emf indicate

A

reduction is occurring on the left (not the normal way though, reduction usually occurs on the right)

55
Q

What is the function of a conductor in a electrochemical cell

A

it connects the 2 electrodes
It allows the transfer of electrons from the anode to the cathode

56
Q

What is the observation of redox of the corrosion of metals (iron)

A

blue/green at the center
pink on the surface/edges

57
Q

What indicator was used during the corrosion of metal experiment

A

ferroxyl indicator

58
Q

What does the blue colour indicate from the ferroxyl indicator

A

Anabolic redox reaction - where reduction occurs

59
Q

What does the pink colour indicate from the ferroxyl indicator

A

Catabolic redox reaction - where oxidation occurs

60
Q
A

Volumetric Flask

61
Q
A

Bulb Pipette

62
Q
A

Burette

63
Q
A

Measuring Cylinder

64
Q
A

Graduated Pipette

DS1101 - S1 Y1 (63 decks)

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