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Higher Chemistry > Unit 2 > Flashcards

Unit 2 Flashcards

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1
Q

Functional Group of Alcohols

A

O-H (Hydroxyl)

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2
Q

General formula for Alcohols

A

CnH2n+2O

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3
Q

Compounds in the same homologous series

A
  • Same functional group
  • Same general formula
  • Similar chemical properties
  • Gradual change in physical properties
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4
Q

General formula for Alkanes

A

CnH2n+2

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5
Q

General formula for Alkenes

A

CnH2n

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6
Q

Functional group of Alkenes

A

C=C (Carbon to carbon double bond)

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7
Q

Test to see if a compound is unsaturated

A

Bromine water and it goes colourless

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8
Q

General formula for cycloalkanes

A

CnH2n

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9
Q

Why are alcohols soluble in water?

A

Hydrogen bonds form between the alcohol molecules and O-H groups (Like dissolves like)

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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

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11
Q

General formula for carboxylic acids

A

CnH2nO2

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12
Q

General formula for esters

A

CnH2nO2

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13
Q

Functional group for esters

A

Ester link or carboxylate (-COO-)

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14
Q

Condensation Reaction

A

When the molecules react to produce a larger molecule and another small molecule (Like water)

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15
Q

Functional group for Carboxylic acids

A

Carboxyl (COOH)

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16
Q

What reactions do alcohols and carboxylic acids to become esters

A

Condensation or Esterification

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17
Q

What functional groups react to form the ester link

A

Hydroxyl and Carboxyl

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18
Q

Advantages of using concentrated sulphuric acid when making an ester

A
  • Catalyst

- Absorbs water formed

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19
Q

Why’s it important in esterification that concentrated sulphuric acid absorbs water

A

Prevents the reverse reaction occurring

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20
Q

Purpose of paper towel in making an ester

A

Acts as a condenser to prevent volatile gases escaping (cooling them down)

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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

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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

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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

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24
Q

Uses for Esters

A

Adhesives, Ink or Paint

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25
Q

How does esters dissolve into other molecules?

A

As esters are non-polar, the molecules they dissolve into are also non-polar
“Like dissolves like” Ldf form

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26
Q

Hydrolysis

A

Large molecules are broken down into smaller molecules by the reaction with water

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27
Q

What happens when esters are hydrolysed?

A

They produce the parent carboxylic acid and parent alcohol

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28
Q

Equation of reversible esterification

A

Acid + Alcohol ↔ Ester + Water

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29
Q

Acid- Catalysed Hydolysis

A

Heating the ester with dilute HCL or H2SO4 provides H+ ions which catalyse the reaction

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30
Q

Alkaline Hydrolysis

A

Alkali’s often are used to catalyse the reaction and mixture heated under reflex

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31
Q

Products of Alkaline Hydrolysis

A

Alcohol and Carboxylic Acid

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32
Q

Advantage(s) of Alkaline Hydrolysis

A
  • Not reversible
  • Higher Yield
  • Easier to separate the products
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33
Q

What do fats and oils provide our body with

A
  • Energy

- A more concentrated source of energy than carbohydrates

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34
Q

What are fats and oils

A

Naturally occurring esters of the alcohol glycerol and long carboxylic chains

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35
Q

Long carboxylic chains

A

“Fatty Acids”

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36
Q

Structure of Glycerol

A 
.......H
........I
H - C - O - H
........I
H - C - O - H
........I
H - C - O - H
........I
........H
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37
Q

Structure of fat or oil

A 
........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
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38
Q

What functional group is in fats and oils and how many of them?

A

3 Ester Links

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39
Q

Other name for Glycerol

A

Propane-1,2,3-triol

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40
Q

Equation for making fats and oils

A

3 fatty Acids + Glycerol -> Fat or Oil

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41
Q

Why has glycerol got a high bpt and viscosity

A
  • 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
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42
Q

Fatty Acid Diagram

A

…………….O
……………..II
VVVVVvC-O-H

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43
Q

How to change an oil to a fat (Summarise)

A
  • 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
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44
Q

Why oils have a lower mpt than fats

A
  • 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
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45
Q

At room temperature, what state is fats and oils in?

A

Fats- Solid

Oils- Liquid

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46
Q

How is triglyceride formed

A

3 moles of fatty acids, 1 mole of glycerol

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47
Q

Diagram of a fat molecule

A 
.............I/\/\/\/\/\
.............I
\/\/\/\/\/I
.............I
.............I/\/\/\/\/\
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48
Q

How will the close packing of fat molecules affect the strength of the ldf

A

Stronger

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49
Q

How will the close packing of fate molecules affect the mpt and bpt

A

Higher

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50
Q

Soap

A

Salt of a fatty acid

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51
Q

How are soaps produced?

A

By alkaline hydrolysis of fats and oils

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52
Q

Emulsifying Regeants

A

Chemicals which can make oil and water become permanently mixed to produce a stable emulsion

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53
Q

Examples of “emulsifying regeants”

A

Soaps and Detergents

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54
Q

How do soaps and detergents act as emulsifying regeants

A

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)

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55
Q

Explain the cleansing action of soap

A

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
Q

‘Hard Water’

A

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
Q

Scum

A

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
Q

Benzene Ring

A

C6H6

59
Q

Emulsions in food

A

Mixtures of oil and water

60
Q

Why would an emulsifier be used?

A

To prevent oil and water components separating into layers

61
Q

How is emulsifiers used in food commonly made?

A

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
Q

What do we need proteins for?

A

Growth and Repair

63
Q

Proteins are the major structural materials of ….

A

Skin, tissue and muscle (Meat)

64
Q

Two types of proteins

A

Fibrous and Globular

65
Q

Structure of fibrous proteins

A
  • 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
Q

Properties of Fibrous proteins

A
  • Insoluble in water
  • Fairly stable to changes in pH and temperature
  • Tough
  • Unreactive
67
Q

What are fibrous proteins used as?

A

Structural proteins

68
Q

Where can fibrous proteins be found in the body?

A
  • Skin
  • Hair
  • Muscle (Meat)
69
Q

What’s the structure of globular proteins

A
  • 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
Q

Properties of globular proteins

A
  • Soluble in water
  • Sensitive to pH changes
  • Changes in temperature
  • Highly reactive
71
Q

What are globular proteins involved in?

A

The maintenance and regulation of life processes including enzymes, hormones (e.g. insulin) and haemoglobin

72
Q

The ‘active site’ in globular proteins

A

Important functional groups from different parts of the polypeptide chain and brought together

73
Q

Enzymes

A
  • Proteins

- Biological Catalysts

74
Q

Enzymes are _____ to particular chemical reactions

A

Specific

75
Q

Certain sequences of amino acids form a region known as the ______

A

Active Site

76
Q

‘Lock and Key’ Method

A

The shape of the active site allows specific reactants known as substrates to attach

77
Q

The enzymes active site and the substrate must have a ______

A

Complementary shape

78
Q

What functional group(s) are in amino acids

A
  • Amino Group(-NH2)

- Carboxyl Group(-COOH)

79
Q

What molecules do amino acids contain

A

Hydrogen, Carbon, Nitrogen and Oxygen

80
Q

How are proteins formed

A

By combining amino acids to form long chain molecules of maybe several thousand amino acid units long (condensation polymers)

81
Q

What is formed when amino acids join together

A
  • An amide link(or peptide link)

- Water

82
Q

How many amino acid units does a tripeptide have?

A

3

83
Q

What’d a longer chain of amino acids called….

A

Polypeptide

84
Q

How many different types of amino acids would be produced during hydrolysis of this section of a polypeptide chain

A

3 different types

85
Q

A primary alcohol (Diagram)

A 
.......O - H
........I
H - C - H
........I
........R
86
Q

Secondary Alcohol (Diagram)

A 
.......O - H
........I
R - C - H
........I
.......R1
87
Q

Tertiary Alcohol (Diagram)

A 
.......O - H
........I
R - C - R3
........I
........R1
88
Q

What happens when proteins are heated?

A

The hydrogen bonds between the chains are broken, causing the proteins to change shape

89
Q

How does water soluble vitamins and flavour molecules dissolve in water?

A

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
Q

How does fat soluble vitamins and flavour molecules dissolve in oil?

A

The fat soluble vitamins and flavour molecules have non-polar fuctional groups like long hydrocarbon chains that can form ldf with oils

91
Q

Primary (1°) alcohol

A

The carbon which carries the -OH group which is only attached to one carbon atom

92
Q

Secondary (2°) alcohol

A

The carbon with the -OH group attached is joined directly to two carbon atoms

93
Q

Tertiary (3°) alcohol

A

The carbon atom holding the -OH group is attached directly to three carbon atoms

94
Q

Combustion of Alcohols

A

Alcohols burn in oxygen and air to produce carbon dioxide and water

95
Q

The word equation for combustion of alcohol

A

Alcohol + Oxygen -> Carbon Dioxide + Water

96
Q

What colour change happens when acidified dichromate solution is added to:
a) 1° alcohol b)2° alcohol c) 3° alcohol

A

A & B= Orange to green

C= No change

97
Q

What happens when a)1° alcohol b) 2° alcohol is heated with hot copper oxide?

A 
A= Goes red (Meaning an acid is formed)
B= No significant change
98
Q

What product(s) are produced when a primary alcohol is oxidised

A

Aldehyde -> Carboxylic Acid

99
Q

What product(s) are produced when a secondary alcohol is oxidised

A

Ketone

100
Q

What product(s) are produced when a tertiary alcohol is oxidised

A

No product (No reaction)

101
Q

What is formed when fats and oils are hydrolysed

A

Fatty Acids and Glycerol

102
Q

Name of the molecule with three hydroxyl groups

A

Trihydric Alcohol or Triol

103
Q

Functional group of aldehyde and ketone

A

Carbonyl Compound

104
Q

General formula of Aldehydes and Ketones

A

CnH2nO

105
Q

What happens when a)Aldehyde b)Ketones are reacted with Benedicts solution

A 
A= Blue to orange with a brick red precipitate
B= No change
106
Q

What happens when a)Aldehydes b)Ketones are reacted with Tollen’s regeant

A 
A= Silver mirror is formed
B= No change
107
Q

What happens when a)Aldehydes b)Ketones are reacted with acidified dichromate

A 
A= Orange to green
B= No change
108
Q

Antioxidants

A
  • Molecules which will prevent oxidation reactions taking place
  • Reducing agents and get oxidised themselves
109
Q

Free radical scavengers

A

They can prevent oxidative damage to molecules by transferring electrons to substances known as free radicals

110
Q

Free Radical

A

A substance that has unpaired electrons

111
Q

What can affect the Vitamin C Content of food

A
  • Ripeness of fruit
  • Age of fruit
  • Variety of fruit
  • How food is processed
  • How it’s cooked
112
Q

What’s the reaction when carboxylic acids are mixed with lithium aluminium hydride

A

It’s reduced in stages to the original aldehyde and alcohol

113
Q

Reduction reaction of a carboxylic acid

A

Involves a decrease in the oxygen to hydrogen ratio (Because oxygen is lost or hydrogen in gained)

114
Q

What can alkanones be reduced to?

A

2° Alcohols

115
Q

Neutralisation

A

The neutral ion in the base replaces the hydrogen of the carboxyl group in the acid

116
Q

Essential Oils

A

Hydrophobic liquids containing mixtures of volatile aroma compounds that evaporate easily in air giving distinctive fragrances

117
Q

What do essential oils contain

A

A mixture of organic compounds, with aromatic molecules

118
Q

Where are essential oils extracted from?

A

From plant material, need to obtain the liquid before it evaporates

119
Q

Steam distillation

A

A mixture of oil and water, but because the two mix, they’re easily separated

120
Q

Why in the condenser of steam distillation does there need to be a lot of the organic compounds (e.g. orange peel)

A

So that the steam must pass through it to extract the oil

121
Q

What’s an important component in essential oils

A

Terpenes

122
Q

How are terpenes formed

A

By joining together isoprene units

123
Q

General formula for terpenes

A

(C5H8)n

124
Q

Why would isoprene units be linked together ‘head to tail’

A

To form linear chains or arranged to form rings

125
Q

How can you reduce photo oxidation (Due to light)

A

It can be stored in brown bottles

126
Q

What’s produced when terpenes are oxidised within plants

A

Some of the compounds responsible for the distinctive aroma of species

127
Q

Ultraviolet Radiation (UV)

A

A high energy form of light, present in sunlight

128
Q

Sun- Block

A

Prevents UV light reaching the skin

129
Q

What can exposure to UV light result in?

A

Molecules gaining sufficient energy for covalent bonds to be broken

130
Q

What does UVA and UVB cause?

A

The breakdown of collagen, creating substances called free radicals that inhibit the natural repair of the skin

131
Q

3 Stages of a free radical chain reaction, initiated by UV light

A

-Initiation, Propagation, termination

132
Q

Initiation

A

UV Provides energy for the homolytic fission of the covalent bond between the halogen atoms to form two free radicals

133
Q

Propagation

A

Free radicals collide with other molecules to give a stable product and another free radical

134
Q

How would an explosion occur in the propagation stage?

A

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
Q

Termination

A

Free radicals are used up when they collide with each other to form a stable molecule

Higher Chemistry (3 decks)

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