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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
This is lecithin
Phosphate
26
This is lecithin
Glycerol
27
This is lecithin
Hydrophobic tail
28
This is lecithin
Hydrophilic head
29
What is the term where a molecule is both hydrophobic and hydrophilic
amphipathic
30
What is the cell membrane made of
- glycerophospholipids - proteins - cholesterol
31
What are factors which influence the integrity of lipid bilayer/ solution polarity (4)
- Extreme temperatures (heat and cold) - Extreme pH - Alcohol - Detergent
32
What is the main lipid which comprises the cell membrane
glycerophospholipids
33
What describes the dynamic nature of a cell membrane
the fluid mosaic model
34
What cell membrane is used in the experiment which test factors which influence cell membrane function and permeability
cell membrane of beetroot
35
Why was the beetroot cell membrane chosen
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
What is the name of the beetroot pigment
betanin (a class of betacyanins)
37
What is the enzyme used in prac 3
a- amylase
38
What is the function of a-amylase
an enzyme (globular protein) found in saliva that hydrolyses starch into glucose
39
What are other enzymes found in saliva
lactoperoxidase and lysozyme which exhibit an antimicrobial role
40
What is the blue-black colour a measure of in prac 3
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
What are some factors which influence activity of enzymes
-temperature - pH
42
What is oxidation
the loss of electrons by a substance, which is said to be oxidised in the process
43
What is reduction
the gain of electrons by a substance which is said to be reduced in the process
44
What is an oxidation-reduction reaction
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
What are the components of a galvanic cell
- 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
What is the function of a salt bridge in a galvanic cell
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
What are electrodes
the 2 solid metals that are connected by the external circuit
48
What is an anode
The electrode where oxidation occurs, this is where electrons are released. Negatively charged since electrons are negatively charged
49
What is a cathode
the electrode where reduction occurs. Positively charged since because it appears to attract the negative electrons
50
What direction does electrons flow in a galvanic cellf
from anode to the cathode
51
What is the name of the equation which calculates emf
Nernst Equation
52
What is the equation for Ecell
Ecell = Ecathode - Eanode
53
What does a positive emf indicate
that reduction occurs on the right in the diagram
54
What does a negative emf indicate
reduction is occurring on the left (not the normal way though, reduction usually occurs on the right)
55
What is the function of a conductor in a electrochemical cell
it connects the 2 electrodes It allows the transfer of electrons from the anode to the cathode
56
What is the observation of redox of the corrosion of metals (iron)
blue/green at the center pink on the surface/edges
57
What indicator was used during the corrosion of metal experiment
ferroxyl indicator
58
What does the blue colour indicate from the ferroxyl indicator
Anabolic redox reaction - where reduction occurs
59
What does the pink colour indicate from the ferroxyl indicator
Catabolic redox reaction - where oxidation occurs
60
Volumetric Flask
61
Bulb Pipette
62
Burette
63
Measuring Cylinder
64
Graduated Pipette

DS1101 - S1 Y1 (63 decks)

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