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Higher Chemistry - 2021/2022 Version 2 > Unit 2 - Nature's Chemistry > Flashcards

Unit 2 - Nature's Chemistry Flashcards

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1
Q

What is the general formula for alkanes?

A

Cn H2n+2

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2
Q

What are the first eight alkanes?

What is the pneumonic to remember these?

A

Methane, Ethane, Propane, Butane, Pentane, Hexane, Heptane, Octane

Monsters Eat People But People Have Hairy Oster’s

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3
Q

Are hydrocarbons soluble in water?

What does this say about their overall polarity?

A

Insoluble

Non-Polar

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4
Q

Are alkanes saturated or unsaturated?

A

Saturated - all carbon to carbon single bonds

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5
Q

What is the general formula for alkenes?

A

Cn H2n

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6
Q

What are the first alkenes?

A

Ethene, Propene, But-1-ene

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7
Q

What does the -1- mean in alkenes?

A

The position of the double bond

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8
Q

Are alkenes saturated or unsaturated?

A

Unsaturated - contain a carbon to carbon double bond

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9
Q

Why isn’t there a methene?

A

Alkenes require a C=C, and methane only has one carbon so cannot form this bond, and therefore no alkene is formed

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10
Q

Why are alkenes more reactive than alkanes?

A

Have a C=C double bond that can be broken in a reaction

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11
Q

What is the test for an alkene?

A

Will turn orange bromine colourless immediately

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12
Q

What is a hydrocarbon?

A

A compound make up of only carbon and hydrogen

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13
Q

What is a homologous series?

A

A family of hydrocarbons with similar chemical properties that share a general formula

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14
Q

What is the general formula for cycloalkanes?

A

CnH2n

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15
Q

What is the first cycloalkane?

A

Cyclopropane

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16
Q

What is the general formula for cycloalkenes?

A

CnH2n-2

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17
Q

What are the steps for naming and alkane?

A

Find the longest chain of hydrogens
Identify the branch and name it
(1 carbon = methyl, 2 carbon = ethyl)
Number the carbons on the chain so the branch is at the lowest number

Write name as : # branch is on chain - branch type chain type
e.g. 2 - methylpentane

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18
Q

What are the steps for naming an alkene?

A

Find the longest possible chain of hydrocarbons
Number the chain so the double bond is at the lowest possible number
Identify branch and name it

Write out as : #branch - branch type chain - # = - type

e.g. 2-methylpent-1-ane

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19
Q

What is an isomer?

A

Compounds with the same molecular formula but a different structural formula

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20
Q

What are the isomers of alkanes?

A

Branched alkanes

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21
Q

What are the isomers of alkenes?

A

Cycloalkanes

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22
Q

What type of hydrocarbon undergoes addition reactions?

A

Alkenes

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23
Q

What is hydrogenation?

A

The reaction between an alkene and hydrogen

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24
Q

What is hydration?

A

The reaction between an alkene and water

Forms and OH branch

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25
Q

In a addition reaction, where do the new molecules add?

A

Where the old double bond was

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26
Q

What is an alcohol?

A

A large group of of organic molecules which contain at least one hydroxide (OH) group as the functional group.

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27
Q

What is the general formula for alcohols?

A

CnH2n+1 OH

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28
Q

How do you name an alcohol?

A

Select longest hydrocarbon chain and name it
Number hydrocarbons from end nearest the hydroxide group - hydroxide > branch
Name branches with their positions

Be prepared to work backwards

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29
Q

Why do alcohols mix well with water?

A

Have hydrogen bonds

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30
Q

What is meant by a dihydric alcohol?

A

An alcohol that contains two hydroxyl groups

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31
Q

What is the removal of water referred to as?

A

Dehydration

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32
Q

What are the three classifications of alcohols?

A

Primary
Secondary
Tertiary

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33
Q

What is a primary alcohol?

A

An alcohol with 2 (or 3) hydrogens attached to the carbon with the hydroxyl group
Attached to 1 carbon

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34
Q

What is a secondary alcohol?

A

An alcohol with one hydrogen atom attached to the carbon with the hydroxyl group
Attached to two carbons

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35
Q

What is a tertiary alcohol?

A

An alcohol that has no hydrogen atoms attached to the carbon with the hydroxyl group
Attached to three carbons (branched)

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36
Q

What are the products from combusting an alcohol?

A

Water and Carbon Dioxide

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37
Q

What is combustion?

A

An extreme form of oxidation

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38
Q

What is the chemical formula for ethanol?

A

C2H5OH

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39
Q

What happens in mild oxidation?

A

Functional group is altered

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40
Q

What type of products are formed when an alcohol undergoes mild oxidation?

A

New organic molecules

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41
Q

What are the mild oxidising agents used to oxidise alcohols?

A 
Acidified potassium dichromate
Acidified potassium permanganate
Benedict's solution
Hot copper(11) oxide
Tollen's reagent
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42
Q

What alcohols don’t go through mild oxidation?

A

Tertiary alcohols

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43
Q

What is the functional group in aldehydes and ketones?

A

Carbonyl group

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44
Q

After undergoing mild oxidation, what do primary alcohols become?

A

Aldehydes (alkanals)

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45
Q

Where is the carbonyl group in aldehydes?

A

At the end (the last/first carbon in the chain)

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46
Q

After undergoing mild oxidation, what does secondary alcohols become?

A

Ketones (alkanones)

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47
Q

Where is the carbonyl group in ketones?

A

In the middle of the chain

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48
Q

What is the general formula for the alkanals?

A

CnH2nO

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49
Q

What is the general formula for the ketones?

A

CnH2nO

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50
Q

What is the relation between the ketones and alkanals?

A

Isomers

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51
Q

What are everyday uses of ketones?

A

Acetone/propanone -> nail polish remover & paint thinner
Acne treatments
Butanone -> production of textiles, varnishes, paint remover, plastics
Cyclohexanone -> production of nylon
Glue
Cleaning agents
Hormones (progesterone, testosterone, cortisone (adrenal) etc)
Tanning
Decreases appetite, used in weight loss programs
Methadone -> cures addiction of opiates (heroin, opium, morphine)

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52
Q

What are everyday uses of aldehydes?

A

Methanal -> embalming
Phenylmethanal (benzaldehyde) -> perfumes, flavourings, cosmetic products, dyes
Ethanal -> sleep inducing drugs, causes hangovers
Pharmaceuticals
Resin

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53
Q

What colour change would you see when an aldehyde mixed with acidified potassium dichromate?

A

Orange to blue/green

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54
Q

What would you see when an aldehyde mixed with benedict’s solution?

A

Blue to brick red

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55
Q

What would you see when an aldehyde mixed with tollen’s reagent?

A

Silver mirror formed

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56
Q

Why can aldehyde’s be further oxidised but ketones cannot?

A

Because of the position of the carbonyl group

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57
Q

What to aldehyde’s form when oxidised further?

A

Alkanoic acids

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58
Q

Where is the carboxyl group in alkanoic acids?

A

At the end of the chain

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59
Q

What is the first member of the alkanoic acids?

A

Methanoic acid

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60
Q

Describe an experiment to test for alkanals?

A

Place it hot water bath with a solution of either acidified potassium dichromate, benedict’s solution or tollen’s reagent.
If a colour change is observed, a reaction has taken place (oxidation) and the solution is an aldehyde

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61
Q

Pentan-3-ol is an example of a _____ alcohol?

A

Secondary

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62
Q

When an alcohol is oxidised what happens to the ratio of oxygen atoms to hydrogen atoms?

A

Increases

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63
Q

What is the functional group in a ketone?

A

Carbonyl group

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64
Q

What is the colour change when acidified potassium dichromate solution reacts with an aldehyde?

A

Orange to blue green

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65
Q

In what way is the structure of an aldehyde different to the structure of a ketone?

A

Carbonyl group on aldehyde is on the first carbon, carbonyl group on ketone is between the start and the end of the carbon chain.

66
Q

What is the colour change when ethanal reacts with acidified potassium dichromate?

A

Ethanal = aldehyde = primary
Further Oxidation
Colour change = Orange to brown/darker

67
Q

What are the names for the reaction in which esters are made?

A

Condensation

Esterification

68
Q

What scent to esters give off?

A

A sweet smell]

69
Q

What happens during a condensation reaction?

A

The functional group from a carboxylic acid and am alcohol functional group

70
Q

How do you name esters?

A

First name = name of alcohol prefix + yl

Second Name = carboxylic acid prefix +oate

71
Q

What ester would be formed by the reaction of ethanoic acid and propan-1-ol?

A

proply ethanoate

72
Q

How would you identify an ester?

A

Ends in oate

Has an ester link/ester functional group

73
Q

What is the functional group of an ester?

A

C double bond O, O

Carbon double bonded to an oxygen and single bonded to another oxygen

74
Q

How should you draw structure for a condensation reaction?

A

Full structural formula

Make functional groups face each other

75
Q

Why do esters form a layer on top of water?

A

Can’t mix with water as water is polar and esters are non polar

76
Q

How would the rate of ester formation be increased?

A

Increased temperature
Use of concentrated sulfuric acid to lower the activation energy
Use of concentrated sulfuric acid to remove water from the products and shift the equilibrium

77
Q

What are the uses of esters?

A 
Pleasant fruity smells
Food
Flavourings
Perfumes
Solvents (industrial)
78
Q

What is the catalyst in esterification?

A

Concentrated sulfuric acid

79
Q

What is the reverse esterification reaction called?

A

Hydrolysis

80
Q

What is the catalyst in a hydrolysis reaction?

A

An alkali

e.g. sodium hydroxide

81
Q

Give examples of natural esters.

A

Fats

Oils

82
Q

Where are natural fats usually sourced from?

A

Animals

83
Q

Where are natural oils usually sourced from?

A

Vegetables and Marine

84
Q

How are natural esters formed?

A

Reaction between long chain carboxylic acid and trihydric alcohols

85
Q

What are long chain carboxylic acids referred to as?

A

Fatty acids

86
Q

Are fatty acids saturated or unsaturated?

A

Either/both

87
Q

What alcohol takes part in the production of natural esters?

A

Propan-1,2,3 - triol

trihydric alcohol

88
Q

How would you tell if a product would be saturated or unsaturated when given a formula?

A

If number of hydrogens > 2 x the number of carbons = saturated
If number of hydrogens < 2 x the number of carbons = unsaturated

89
Q

Are fats saturated or unsaturated?

A

Saturated?

90
Q

Are oils saturated or unsaturated?

A

Unsaturated

91
Q

What is the ratio for glycerol to fatty acid chains?

A

1 glycerol molecule : 3 fatty chains

92
Q

Why do fats have higher melting points than oils?

A

Molecules are packed closely together so have stronger Van Der Waals forces between molecules increasing the melting and boiling point

93
Q

Why so oils have a lower melting point than fats?

A

Molecules are unable to pack closely together due to their irregular structure resulting in weaker van der waals forces and so lower melting and boiling points

94
Q

What is hydrogenation?

A

A reaction which converts unsaturated compounds into more saturated ones
‘hardening reaction’

95
Q

What is hydrogenation used to do?

A

Change oils into margarine

96
Q

What catalyst is used in hydrogenation reactions?

A

Nickel

97
Q

What happens in a hydrogenation reaction?

A

Hydrogen is added to compounds to remove/reduce the number of carbon to carbon double bonds

98
Q

How can the degree of saturation in a fat or oil be determined?

A

By the iodine number

99
Q

What does a greater iodine number suggest?

A

More c=c double bonds

100
Q

How are soaps made?

A

Hydrolysis of fats and oils with an alkali

101
Q

What are the products of an alkali hydrolysis of fats and oils?

A

Water soluble ionic salt of the carboxylic acid

Glycerol

102
Q

What are the two parts of soap?

A

Head and tail

103
Q

What are the properties of the head and tail of soap?

A

Head -> hydrophilic, polar, water soluble, ionic

Tail -> hydrophobic, non polar, oil soluble, covalent

104
Q

Describe the cleaning action of soap

A

Non polar hydrophobic tail attracts non-polar fat/oil molecules
Polar hydrophilic heads are attracted to polar water molecules
Large fatty molecules are broken into small lumps called micelles resulting in a suspension of fatty material in the water

105
Q

What is an emulsifier?

A

Molecule that allows non polar and polar molecules to mix (i.e. soap)

106
Q

What is emulsion?

A

Mixture of non polar and polar substances

107
Q

Why do we need proteins?

A

For growth and repair

108
Q

What are proteins components of?

A

Animal tissue :muscle, hair, nails, skin

109
Q

What are proteins made from?

A

Amino acids - hydrogen and nitrogen

110
Q

What is the test to confirm the presence of nitrogen?

A

Soda lime with protein heated up in a boiling tube with a mineral wool bung and a piece of wet pH paper at the mouth.
pH paper should turn blue

111
Q

What are proteins in chemistry?

A

Natural polymers made up of amino acid monomers

112
Q

What functional group do amino acids have?

A

Carboxyl and amine

113
Q

What is the amine functional group?

A

NH2

114
Q

What is an essential amino acid?

A

An amino acid that we get from our diet

115
Q

What can happen if an essential amino acid is missing from our diet?

A

Deficiencies

116
Q

What reaction turns monomer amino acids into a polymer protein?

A

Condensation polymerisation

117
Q

How would you identify a protein?

A

From the functional group

118
Q

What is the functional group in proteins?

A

Amide / Peptide Link

119
Q

Give the reactants and products of a condensation polymerisation reaction.

A

Reactants -> amino acids

Products -> proteins and water

120
Q

In a condensation polymerisation reaction, what does the water form from?

A

OH off of carboxyl group

H off of Amine group

121
Q

What is the polarity of amide links?

A

Polar

122
Q

What intermolecular forces are present in proteins and where?

A

Hydrogen bonds between H and O

123
Q

What is the reverse reaction to a condensation polymerisation reaction?

A

Hydrolysis

124
Q

Where does the water add to in a hydrolysis of a protein?

A

OH onto C=0

H onto nitrogen

125
Q

What are the two classifications of proteins?

A

Fibrous

Globular

126
Q

What are the characteristics of fibrous proteins?

A

Long and thin - penne pasta

Major structural materials of animal tissue

127
Q

Give examples of fibrous proteins.

A

Skin
Muscle
Hair
Nails

128
Q

What is the main purpose of globular proteins?

A

Maintenance and regulation life processes

Spaghetti structure

129
Q

Give examples of globular proteins.

A

Enzymes
Hormones
e.g. insulin and haemoglobin

130
Q

What are enzymes?

A

Natural catalysts that decrease the activation energy of biological reactions so they can take place at body temperature

131
Q

Give a method of making a soap

A

Weight out mass of oil in a beaker
Add dripping
Add a shaving of soap
Slowly heat to 95 degrees with a Bunsen
Weigh sample of sodium hydroxide pellets and dissolve in water
Add sodium hydroxide solution to hot fat mixture slowly
Mixture should stiffen
Cool solution and add water at 65 degrees
Stir and heat for another 30 minutes to form a thick paste
Heat hot brine and add to solution
Stir until soap breaks away
Leave overnight

132
Q

How do we taste food?

A

Through sense of smell and taste

133
Q

What is volatility?

A

A measure of ease of evaporation

134
Q

Why are small non polar easier to evaporate than larger non polar molecules?

A

Have very low mp and bp

135
Q

When do volatile flavour molecules evaporate?

A

When they have a low boiling point

136
Q

What determines if a flavour molecule is water or fat soluble?

A

The structure of the molecule

Type of intermolecular bonding

137
Q

What intermolecular force do very volatile molecules have?

A

London Dispersion Forces

138
Q

What are antioxidants?

A

Reducing agents

139
Q

What do antioxidants do?

A

Provide electrons to prevent the oxidation of fats/oils of foods
Prolong shelf life

140
Q

Give two pieces of evidence for the oxidation of ascorbic acid.

A

Loss of electrons

Decreased O:H ratio

141
Q

How many carbons are present in one isoprene unit?

A

5

142
Q

What do fragrances contain?

A

Essential oils

143
Q

What is meant by an essential oil?

A

An oil that gives off an essence (flavour, smell/aroma)

144
Q

Why do essential oils evaporate easily?

A

Volatile (low bp)

145
Q

Are essential oils polar or non-polar?

A

Non polar

146
Q

What are terpenes?

A

Key component of essential oils

147
Q

What is the systematic name for isoprene?

A

2-methylbutan-1,3-diene

148
Q

What is the general formula for isoprene?

A

(C5H8)n

149
Q

What are terpenes made up of?

A

Linked isoprene units

150
Q

How can isoprene’s link together?

A

Head to tail - linear

Ring structure

151
Q

What is an oxidised terpene known as?

A

Terpanoid

152
Q

What types of UV pose a threat to humans?

A

UVA and UVB

153
Q

How does sunblock work?

A

Chemicals absorb UV radiation

Reflect UV radiation away from the skin

154
Q

What is a free radical?

A

Atoms/molecules which have unpaired electrons that makes them extremely reactive with potential to harm cells

155
Q

What are the stages of a free radical chain reaction?

A

Initiation
Propagation
Termination

156
Q

How do you identify the initiation stage of free radicals?

A

Free radicals are on the right hand side

157
Q

How do you identify the propagation stage of free radicals?

A

Free radicals are on both sides of the equation

158
Q

How do you identify the termination stage of free radicals?

A

Free radicals are on left hand side of the equation

159
Q

What are free radical scavengers also known as?

A

Antioxidants

160
Q

What are free radical scavengers?

A

Molecules react with free radicals to produce stable molecules and thus terminates the reaction

Higher Chemistry - 2021/2022 Version 2 (3 decks)

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