Unit 2 Flashcards
1
Q
Functional Group of Alcohols
A
O-H (Hydroxyl)
2
Q
General formula for Alcohols
A
CnH2n+2O
3
Q
Compounds in the same homologous series
A
- Same functional group
- Same general formula
- Similar chemical properties
- Gradual change in physical properties
4
Q
General formula for Alkanes
A
CnH2n+2
5
Q
General formula for Alkenes
A
CnH2n
6
Q
Functional group of Alkenes
A
C=C (Carbon to carbon double bond)
7
Q
Test to see if a compound is unsaturated
A
Bromine water and it goes colourless
8
Q
General formula for cycloalkanes
A
CnH2n
9
Q
Why are alcohols soluble in water?
A
Hydrogen bonds form between the alcohol molecules and O-H groups (Like dissolves like)
10
Q
Why do alcohols have a higher bpt than hydrocarbons with a similar mass?
A
Hydrogen bonds between the alcohols need to be broken which takes much more energy than to break the ldf between hydrocarbons
11
Q
General formula for carboxylic acids
A
CnH2nO2
12
Q
General formula for esters
A
CnH2nO2
13
Q
Functional group for esters
A
Ester link or carboxylate (-COO-)
14
Q
Condensation Reaction
A
When the molecules react to produce a larger molecule and another small molecule (Like water)
15
Q
Functional group for Carboxylic acids
A
Carboxyl (COOH)
16
Q
What reactions do alcohols and carboxylic acids to become esters
A
Condensation or Esterification
17
Q
What functional groups react to form the ester link
A
Hydroxyl and Carboxyl
18
Q
Advantages of using concentrated sulphuric acid when making an ester
A
- Catalyst
- Absorbs water formed
19
Q
Why’s it important in esterification that concentrated sulphuric acid absorbs water
A
Prevents the reverse reaction occurring
20
Q
Purpose of paper towel in making an ester
A
Acts as a condenser to prevent volatile gases escaping (cooling them down)
21
Q
Why’s the reaction mixture heated in a water bath in Esterification
A
To increase the rate of reaction, a Bunsen can’t be used as the reaction is flammable
22
Q
Why’s the mixture poured into sodium hydrogen carbonate in Esterification?
A
To neutralise the concentrated sulphuric acid catalyst and any excess carboxylic acid
23
Q
Why are alcohols and carboxylic acids soluble in water whereas esters are insoluble in water?
A
Alcohols are very soluble due to the polar O-H groups that form H-bonds with water. Carboxylic acids are the same but due to the COOH group. Esters are insoluble as the molecule is mostly non-polar and can’t form H-bonds with water
24
Q
Uses for Esters
A
Adhesives, Ink or Paint
25
How does esters dissolve into other molecules?
As esters are non-polar, the molecules they dissolve into are also non-polar
"Like dissolves like" Ldf form
26
Hydrolysis
Large molecules are broken down into smaller molecules by the reaction with water
27
What happens when esters are hydrolysed?
They produce the parent carboxylic acid and parent alcohol
28
Equation of reversible esterification
Acid + Alcohol ↔ Ester + Water
29
Acid- Catalysed Hydolysis
Heating the ester with dilute HCL or H2SO4 provides H+ ions which catalyse the reaction
30
Alkaline Hydrolysis
Alkali's often are used to catalyse the reaction and mixture heated under reflex
31
Products of Alkaline Hydrolysis
Alcohol and Carboxylic Acid
32
Advantage(s) of Alkaline Hydrolysis
- Not reversible
- Higher Yield
- Easier to separate the products
33
What do fats and oils provide our body with
- Energy
| - A more concentrated source of energy than carbohydrates
34
What are fats and oils
Naturally occurring esters of the alcohol glycerol and long carboxylic chains
35
Long carboxylic chains
"Fatty Acids"
36
Structure of Glycerol
```
.......H
........I
H - C - O - H
........I
H - C - O - H
........I
H - C - O - H
........I
........H
```
37
Structure of fat or oil
```
........H........O
........I...........II
H - C - O - C - R1
........I...........O
........I............II
H - C - O - C - R2
........I............O
........I.............II
H - C - O - C - R3
........I
.......H
```
38
What functional group is in fats and oils and how many of them?
3 Ester Links
39
Other name for Glycerol
Propane-1,2,3-triol
40
Equation for making fats and oils
3 fatty Acids + Glycerol -> Fat or Oil
41
Why has glycerol got a high bpt and viscosity
- Glycerol has 3 O-H groups allowing lots of H-bonds to form between the glycerol molecules
- As lots of energy is needed to break the hydrogen bonds
42
Fatty Acid Diagram
................O
.................II
VVVVVvC-O-H
43
How to change an oil to a fat (Summarise)
- Hydrogenation (Addition of Hydrogen)
- In the oil the C=C is changed to C-C bonds making the molecules more saturated and more linear
- Molecules pack more closely, leading to stronger ldf between chains
- More energy to break, leading to a higher mpt and bpt
44
Why oils have a lower mpt than fats
- Saturated hydrocarbons so not linear
- Less energy to break, leading to a lower mpt and liquid oil
- Molecules don't pack closely, weaker ldf between chains
45
At room temperature, what state is fats and oils in?
Fats- Solid
| Oils- Liquid
46
How is triglyceride formed
3 moles of fatty acids, 1 mole of glycerol
47
Diagram of a fat molecule
```
.............I/\/\/\/\/\
.............I
\/\/\/\/\/I
.............I
.............I/\/\/\/\/\
```
48
How will the close packing of fat molecules affect the strength of the ldf
Stronger
49
How will the close packing of fate molecules affect the mpt and bpt
Higher
50
Soap
Salt of a fatty acid
51
How are soaps produced?
By alkaline hydrolysis of fats and oils
52
Emulsifying Regeants
Chemicals which can make oil and water become permanently mixed to produce a stable emulsion
53
Examples of "emulsifying regeants"
Soaps and Detergents
54
How do soaps and detergents act as emulsifying regeants
Soap molecules have a long non-polar hydrocarbon chain 'tail' which is readily soluble in non-polar (Hydrophobic) compounds and a polar ionic carboxylate 'head' which is water soluble (Hydrophylic)
55
Explain the cleansing action of soap
During cleaning, the hydrophobic tails of the soap dissolve in the droplet of the grease, whilst the hydrophylic heads face out into the surrounding water, resulting in ball like structures
56
'Hard Water'
Water that contains a high concentration of calcium and magnesium ions which make it hard to form a lather of soap- a white scum forms instead
57
Scum
The name given to the precipitate when the Ca2+ and Mg2+ ions in hard water and react with the fatty acid part of the soap
58
Benzene Ring
C6H6
59
Emulsions in food
Mixtures of oil and water
60
Why would an emulsifier be used?
To prevent oil and water components separating into layers
61
How is emulsifiers used in food commonly made?
By reacting edible oils with glycerol to form molecules in which either one or two fatty acid groups are linked to a glycerol backbone rather than the three normally found in edible oils
62
What do we need proteins for?
Growth and Repair
63
Proteins are the major structural materials of ....
Skin, tissue and muscle (Meat)
64
Two types of proteins
Fibrous and Globular
65
Structure of fibrous proteins
- Long, thin structure
- Molecular chains are interwoven to form multi-strand cables due to the intermolecular (Hydrogen) bonding between the carboxyl and amino groups in adjacent polypeptide chains
66
Properties of Fibrous proteins
- Insoluble in water
- Fairly stable to changes in pH and temperature
- Tough
- Unreactive
67
What are fibrous proteins used as?
Structural proteins
68
Where can fibrous proteins be found in the body?
- Skin
- Hair
- Muscle (Meat)
69
What's the structure of globular proteins
- Consists of spiral chains which are folded into compact units by hydrogen bonds
- The hydrogen bonds form between the carboxyl and amino groups of the amino acids in the same polypeptide chains to produce spirals
70
Properties of globular proteins
- Soluble in water
- Sensitive to pH changes
- Changes in temperature
- Highly reactive
71
What are globular proteins involved in?
The maintenance and regulation of life processes including enzymes, hormones (e.g. insulin) and haemoglobin
72
The 'active site' in globular proteins
Important functional groups from different parts of the polypeptide chain and brought together
73
Enzymes
- Proteins
| - Biological Catalysts
74
Enzymes are _____ to particular chemical reactions
Specific
75
Certain sequences of amino acids form a region known as the ______
Active Site
76
'Lock and Key' Method
The shape of the active site allows specific reactants known as substrates to attach
77
The enzymes active site and the substrate must have a ______
Complementary shape
78
What functional group(s) are in amino acids
- Amino Group(-NH2)
| - Carboxyl Group(-COOH)
79
What molecules do amino acids contain
Hydrogen, Carbon, Nitrogen and Oxygen
80
How are proteins formed
By combining amino acids to form long chain molecules of maybe several thousand amino acid units long (condensation polymers)
81
What is formed when amino acids join together
- An amide link(or peptide link)
| - Water
82
How many amino acid units does a tripeptide have?
3
83
What'd a longer chain of amino acids called....
Polypeptide
84
How many different types of amino acids would be produced during hydrolysis of this section of a polypeptide chain
3 different types
85
A primary alcohol (Diagram)
```
.......O - H
........I
H - C - H
........I
........R
```
86
Secondary Alcohol (Diagram)
```
.......O - H
........I
R - C - H
........I
.......R1
```
87
Tertiary Alcohol (Diagram)
```
.......O - H
........I
R - C - R3
........I
........R1
```
88
What happens when proteins are heated?
The hydrogen bonds between the chains are broken, causing the proteins to change shape
89
How does water soluble vitamins and flavour molecules dissolve in water?
The water soluble vitamins and flavour molecules have polar functional groups like OH, COOH, NH2, C=O, COO which can form hydrogen bonds with water
90
How does fat soluble vitamins and flavour molecules dissolve in oil?
The fat soluble vitamins and flavour molecules have non-polar fuctional groups like long hydrocarbon chains that can form ldf with oils
91
Primary (1°) alcohol
The carbon which carries the -OH group which is only attached to one carbon atom
92
Secondary (2°) alcohol
The carbon with the -OH group attached is joined directly to two carbon atoms
93
Tertiary (3°) alcohol
The carbon atom holding the -OH group is attached directly to three carbon atoms
94
Combustion of Alcohols
Alcohols burn in oxygen and air to produce carbon dioxide and water
95
The word equation for combustion of alcohol
Alcohol + Oxygen -> Carbon Dioxide + Water
96
What colour change happens when acidified dichromate solution is added to:
a) 1° alcohol b)2° alcohol c) 3° alcohol
A & B= Orange to green
| C= No change
97
What happens when a)1° alcohol b) 2° alcohol is heated with hot copper oxide?
```
A= Goes red (Meaning an acid is formed)
B= No significant change
```
98
What product(s) are produced when a primary alcohol is oxidised
Aldehyde -> Carboxylic Acid
99
What product(s) are produced when a secondary alcohol is oxidised
Ketone
100
What product(s) are produced when a tertiary alcohol is oxidised
No product (No reaction)
101
What is formed when fats and oils are hydrolysed
Fatty Acids and Glycerol
102
Name of the molecule with three hydroxyl groups
Trihydric Alcohol or Triol
103
Functional group of aldehyde and ketone
Carbonyl Compound
104
General formula of Aldehydes and Ketones
CnH2nO
105
What happens when a)Aldehyde b)Ketones are reacted with Benedicts solution
```
A= Blue to orange with a brick red precipitate
B= No change
```
106
What happens when a)Aldehydes b)Ketones are reacted with Tollen's regeant
```
A= Silver mirror is formed
B= No change
```
107
What happens when a)Aldehydes b)Ketones are reacted with acidified dichromate
```
A= Orange to green
B= No change
```
108
Antioxidants
- Molecules which will prevent oxidation reactions taking place
- Reducing agents and get oxidised themselves
109
Free radical scavengers
They can prevent oxidative damage to molecules by transferring electrons to substances known as free radicals
110
Free Radical
A substance that has unpaired electrons
111
What can affect the Vitamin C Content of food
- Ripeness of fruit
- Age of fruit
- Variety of fruit
- How food is processed
- How it's cooked
112
What's the reaction when carboxylic acids are mixed with lithium aluminium hydride
It's reduced in stages to the original aldehyde and alcohol
113
Reduction reaction of a carboxylic acid
Involves a decrease in the oxygen to hydrogen ratio (Because oxygen is lost or hydrogen in gained)
114
What can alkanones be reduced to?
2° Alcohols
115
Neutralisation
The neutral ion in the base replaces the hydrogen of the carboxyl group in the acid
116
Essential Oils
Hydrophobic liquids containing mixtures of volatile aroma compounds that evaporate easily in air giving distinctive fragrances
117
What do essential oils contain
A mixture of organic compounds, with aromatic molecules
118
Where are essential oils extracted from?
From plant material, need to obtain the liquid before it evaporates
119
Steam distillation
A mixture of oil and water, but because the two mix, they're easily separated
120
Why in the condenser of steam distillation does there need to be a lot of the organic compounds (e.g. orange peel)
So that the steam must pass through it to extract the oil
121
What's an important component in essential oils
Terpenes
122
How are terpenes formed
By joining together isoprene units
123
General formula for terpenes
(C5H8)n
124
Why would isoprene units be linked together 'head to tail'
To form linear chains or arranged to form rings
125
How can you reduce photo oxidation (Due to light)
It can be stored in brown bottles
126
What's produced when terpenes are oxidised within plants
Some of the compounds responsible for the distinctive aroma of species
127
Ultraviolet Radiation (UV)
A high energy form of light, present in sunlight
128
Sun- Block
Prevents UV light reaching the skin
129
What can exposure to UV light result in?
Molecules gaining sufficient energy for covalent bonds to be broken
130
What does UVA and UVB cause?
The breakdown of collagen, creating substances called free radicals that inhibit the natural repair of the skin
131
3 Stages of a free radical chain reaction, initiated by UV light
-Initiation, Propagation, termination
132
Initiation
UV Provides energy for the homolytic fission of the covalent bond between the halogen atoms to form two free radicals
133
Propagation
Free radicals collide with other molecules to give a stable product and another free radical
134
How would an explosion occur in the propagation stage?
A fast chain reaction occurs because while free radicals are being regenerated during the propagation stage, new free radicals are being produced in the initiation stage
135
Termination
Free radicals are used up when they collide with each other to form a stable molecule
