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Higher Chemistry > UNIT 2 > Flashcards

UNIT 2 Flashcards

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1
Q

what are the rules to use when naming hydrocarbons?

A

identify the longest chain of carbons and link the alkane, alkene or cycloalkane to a number (e.g prop - 3)

for alkenes, count from the side of the molecule that gives the double bond the lowest number

for branches, name them according to the number of the carbon atoms (methyl, ethyl etc) making sure you count from the side of the molecule that gives your branch the lowest number

where there are branches and double bonds, count from the side that gives your double bond the lowest number

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2
Q

what are isomers?

A

they are compounds that have the same molecular formula but different structural formulae

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3
Q

what are saturated compounds?

A

compounds with single carbon bonds are known as saturated

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4
Q

what are unsaturated compounds?

A

compounds containing at least one carbon-carbon double bond are described as unsaturated

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5
Q

how to tell if a product is saturated or unsaturated?

A

using bromine solution as unsaturated products decolourise bromine solution

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6
Q

what type of compound can take part in addition reactions?

A

unsaturated compounds

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7
Q

what increases as the size of hydrocarbon molecules increases and why?

A

the boiling point increases as the size of hydrocarbon molecules increases as LDF interactions are found between hydrocarbon molecules and LDF VDW interactions get stronger as the number of electrons increases. longer molecules have more electrons than smaller molecules

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8
Q

volatile meaning?

A

evaporates easily

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9
Q

which type of hydrocarbon is he most volatile?

A

larger hydrocarbons are less volatile than smaller ones

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10
Q

why cant hydrocarbons dissolve in water?

A

hydrocarbon’s are non-polar and water is polar so therefore they do not dissolve in water

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11
Q

what are hydrocarbons useful for?

A

they are useful solvents for dissolving non-polar compounds

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12
Q

what do alcohols contain?

A

a hydroxyl (-OH) functional group

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13
Q

what is a primary alcohol?

A

this is when the -OH group is attached to a C atom with at least two H atoms

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14
Q

what is a secondary alcohol?

A

the -OH group is attached to a C atom with one H atom

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15
Q

what is a tertiary alcohol?

A

the -OH group is attached to a C atom that is not attached to any H atoms

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16
Q

what kind of bonds can alcohols form and how?

A

alcohol molecules contain a hydroxyl group and they can form hydrogen bonds to neighbouring alcohol molecules

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17
Q

why do alcohols have a higher mp/bp to molecules of similar relative molecular mass?

A

hydrogen bonds present in alcohols are stronger than LDF and PD-PDI and therefore alcohols have higher mp/bp. The large increase in the boiling point of alcohols as the number of hydroxyl groups increases is caused by a greater degree of hydrogen bonding between the molecules.

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18
Q

what does the number of hydroxyl groups present in an alcohol indicate?

A

more hydroxyl groups = higher viscosity

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19
Q

can alcohols dissolve in water?

A

yes, they are polar due to hydrogen bonding so therefore they can dissolve in water

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20
Q

general formula and functional group of alkenes?

A

general formula - CnH2n

functional group - does not have

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21
Q

general formula and functional group of alkanes?

A

general formula - CnH2n+2

functional group - No functional group. Molecules end with CH3

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22
Q

general formula and functional group of cycloalkanes?

A

general formula - CnH2n

functional group - no specific functional group. ring of c-c bonds.

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23
Q

general formula and functional group of alcohols?

A

general formula - CnH2n+1OH

functional group - OH

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24
Q

general formula and functional group of carboxylic acids?

A

general formula - CnH2n+1COOH

functional group - COOH

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25
Q

why are alkenes more reactive?

A

Alkenes are more reactive than alkanes and cycloalkanes because they have a double bond.

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26
Q

what happens in an addition reaction?

A

In an addition reaction, the double bond of the alkene partially breaks when the reactant molecule attacks and adds on across it.

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27
Q

example of addition reaction?

A

Addition of bromine water can be used as a test for unsaturation.
Alkenes quickly turn bromine water from red/brown to colourless, while alkanes and cycloalkanes do not.

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28
Q

what is different about cycloalkanes from alkenes (they have the same general formula)?

A

Even though they have the same general formula as the alkenes, the cycloalkanes are saturated and contain only single bonds. This means that they do not quickly decolourise bromine solution. Cyloalkanes are isomers of the alkenes.

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29
Q

what are the rules to naming an alcohol?

A
  • Find the longest carbon chain and name it.
  • Number the carbon atoms in the chain so that the functional group (in this case, the hydroxyl group) has the lowest possible number.
  • Identify any branches joined onto the main chain and name them.
  • Identify each branch by a number indicating its position. If more than one branch is present then a prefix must be used.
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30
Q

what type of reactions can carboxylic acids undergo?

A

Carboxylic acids can undergo reduction reactions. Reduction is the opposite of oxidation.

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31
Q

oxidation defninition?

A

it can be defined as the removal of oxygen or the addition of hydrogen to a molecule.

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32
Q

what do carboxylic acids react with in neutralisation reactions?

A

Carboxylic acids can also react with bases to form salt and water in neutralisation reactions.

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33
Q

what type of reaction forms an ester?

A

Esters are formed by the condensation reaction between an alcohol and a carboxylic acid. This is known as esterification.

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34
Q

what is a condensation reaction?

A

In a condensation reaction, two molecules join and produce a larger molecule whilst eliminating a small molecule.

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35
Q

what is an ester link?

A

The functional group (-COO) is known as the ester link

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36
Q

how to name an ester?

A
  • change the name of the parent alcohol to end in –yl
  • change the name of the parent acid to end in –oate
  • alcohol name goes to the front, acid name to the back
  • = O always on acid
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37
Q

how can you form an ester out of an alcohol?

A

To make an ester, a hydrogen atom must be removed from the hydroxyl group (–OH) of the alcohol.

The –OH portion of the acid’s carboxyl group must also be removed. The hydrogren atom and the -OH combine to form a water molecule (H2O).

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38
Q

how can esters be broken up?

A

The breaking up of an ester can be achieved by heating the ester with an alkali such as sodium hydroxide.

This is an example of a hydrolysis reaction

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39
Q

what is a hydrolysis reaction?

A

a hydrolysis reaction (the opposite of a condensation reaction) is when a water molecule is added and breaks up the structure.

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40
Q

why are fats and oils useful?

A

Fats and oils are naturally occurring esters that are used in our diets to provide us with energy. They play an important role in the transport of vitamins that are soluble in fats around the human body.

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41
Q

how are fats and oils formed?

A

All fats and oils are naturally occurring esters, formed from condensation reactions between the alcohol glycerol and fatty acids

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42
Q

what is glycerol?

A

Glycerol is also known by its systematic name propane-1,2,3-triol. It is a triol, meaning that it has three hydroxyl functional groups

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43
Q

what are fatty acids?

A

Fatty acids are long chain carboxylic acids ranging from C4 to C28.

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44
Q

what are triglycerides?

A

The acid molecules can either be saturated or unsaturated. The fats and oils formed are also known as triglycerides. they are esters.

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45
Q

why do oils have a lower melting point than fats?

A

The lower melting point of oils is related to the higher degree of unsaturation. The presence of carbon to carbon double bonds in the oil molecules distorts the long fatty acid chains and the molecule’s shape. As a result the molecules cannot pack closely together. This means that the LDF bonds are weaker

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46
Q

what do oils contain that fats do not?

A

Oils (liquids at room temperature) contain more carbon to carbon double bonds than fats (solid at room temperature).

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47
Q

fats and oils are formed from a ______ condensation reaction

A

reversible

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48
Q

why do fats have a higher mp/bp than oils?

A

due to efficient packing

49
Q

how does poor packaging affect mp/bp?

A

The poorer packing in oils makes London dispersion forces between the oil molecules weaker than between fat molecules. Less heat energy is needed to separate oil molecules, so oils have lower melting points than fats.

50
Q

how can the melting point of an oil be increased?

A

To increase the melting point of an oil, addition reactions between the double bonds and hydrogen can take place. This reduces unsaturation and causes hardening (hydrogenation)

51
Q

what are soaps?

A

Soaps play a vital role in keeping clean. They are salts made from the alkaline hydrolysis of fats and oils (triglycerides).

52
Q

how many ester links do fat molecules contain and what does this mean?

A

Fat molecules contain three ester links. This mean they can be hydrolysed when they are heated with sodium hydroxide or potassium hydroxide. This results in the formation of glycerol and a salt - soap.

53
Q

what are fats and oils made of?

A

Fats and oils are esters made from glycerol and long chain fatty acids

54
Q

what does a soap molecule contain?

A

Each molecule consists of a long non-polar covalent hydrocarbon (hydrophobic) ‘tail’ and a polar, ionic (hydrophilic) ‘head’ where the charge is.

55
Q

how does the structure of soap help it in cleaning?

A

This structure explains the cleansing action of soap as the non-polar hydrophobic ‘tail’ dissolves in non-polar substances such as grease while the polar ‘head’ will not.

Once mixed properly, the grease is broken up into small ball-like structures (micelles) and held in suspension in the water by the repulsion of the negatively charged ionic heads.

56
Q

what is an emulsion?

A

an emulsion is a liquid that contains small droplets of another liquid. This suspension of small grease droplets in water is called an emulsion.

57
Q

what are detergents?

A

Detergents are a family of compounds that are similar to soaps and work in a similar way. They are more useful in areas where hard water is present

58
Q

what is hard water?

A

water containing a high level of dissolved metal ions

59
Q

what happens when soap is used on hard water?

A

insoluble precipitate (scum) is formed when soap is used with hard water

60
Q

what is scum?

A

an insoluble precipitate formed when soap mixes with hard water

61
Q

what is the structure of a detergent?

A

detergents have a hydrophobic head and a hydrophilic body

62
Q

what is an emulsifier?

A

it is a substance that helps to bring two insoluble liquids together - soap is an example because it helps bring oil and water together

63
Q

what is a common way of making a emulsifier?

A

by hydrolysing a fat or oil, one or two fatty acids are removed so the emulsifier made will contain one or two hydroxyl groups.

64
Q

what is the structure of an amino acid?

A

they contain the amine group and the carboxyl group

65
Q

what type of reaction occurs to form proteins?

A

amino acids react together in a condensation reaction to form proteins. they do this by linking the -OH of the carboxyl group and the -H of the amino group to form water.

66
Q

what is the link formed between amino acids called?

A

the peptide/amide link

67
Q

what are fibrous protein molecules?

A

Fibrous protein molecules are long, spiral chains that are folded to form strong structures.

68
Q

what are some biological uses of proteins?

A

forming structures (hair and skin) and acting as hormones

69
Q

what are essential amino acids?

A

The body cannot make all the amino acids required to build different proteins. It relies on protein intake from our diet to supply the essential amino acids.

70
Q

what do different amino acid molecules make?

A

Different amino acid molecules can be joined together in different orders within our bodies to form different proteins.

71
Q

how can proteins be broken down?

A

proteins can be broken down by hydrolysis. Water molecules break apart the peptide links of the protein molecule, leaving separate amino acid molecules.

72
Q

how does the digestion of proteins occur?

A

During digestion, enzymes in our bodies break the proteins we eat down into amino acids (by hydrolysis).

73
Q

how are amino acids used by the body?

A

These amino acids are transported around the body by blood. In the bloodstream, condensation reactions build the amino acids up to produce proteins required by the body.

74
Q

how does the process of breaking down a protein occur?

A

this process requires water as an H-atom must be added to the -NH group and an -OH must be added to the -C=O group (hydrolysis)

75
Q

define amino?

A

the -NH2 group present in amines and amino acids

76
Q

define carboxyl?

A

the -COOH group found in carboxylic acids and amino acids

77
Q

where is the amide link located?

A

a bond formed between an amino group and a carboxyl group

78
Q

how can proteins affect cooking of foods?

A

During cooking, when the proteins are heated, the molecules become agitated and move around causing the intermolecular bonds between molecules to be broken.

This allows the protein to denature (change shape) which changes the texture of foods.

79
Q

what are globular proteins?

A

They have their spiral chains folded into spherical shapes and are generally soluble in water.

the protein chains are arranged in a 3D shape, , they are held in these shapes by intermolecular bonding between the side chains of the amino acids involved.

80
Q

what type of intermolecular bonding is present in proteins?

A

proteins can form hydrogen bonds as they contain an -NH group. these hydrogen bonds allow the long chains to form a variety of shapes

81
Q

what does denaturing mean?

A

altering the shape of a protein by breaking the bonds between protein chains. this can be caused by changes in temperature and pH. denaturing an enzyme can stop it from working as proteins with specific shapes are needed to catalyse specific reactions

82
Q

what is an enzyme?

A

a protein that acts as a biological catalyst - they have specific shapes

83
Q

what causes complex shapes in proteins?

A

common shapes are spirals and sheets but complex shapes can be formed as the protein chains can hydrogen bond to neighbouring protein chains

84
Q

what is the process of oxidation for primary alcohols?

A

primary –> aldehyde –> carboxylic acid

85
Q

what is the process of oxidation for secondary alcohols?

A

secondary –> ketone –> ketones aren’t oxidised using mild oxidising agents

86
Q

what is the process of oxidation for tertiary alcohols?

A

tertiary alcohols aren’t oxidised using mild oxidising agents

87
Q

what happens when chemicals in food are exposed to oxygen?

A

When chemicals in food are exposed to oxygen in the air, their chemical composition changes and they begin to break down.

88
Q

how do animals and plants tissues slow down the oxidation of food?

A

Animal and plant tissues contain antioxidant molecules to prevent this from happening. These molecules can slow the rate of oxidation in our foods. But left unattended, foods will lose their nutritional value as they begin to discolour and break down.

89
Q

what are some examples of oxidising agents?

A

acidified potassium dichromate solution (orange to green)
Tollen’s reagent (brown to silver-mirror)
Fehling’s solution (blue to red)

90
Q

how can aldehydes be distinguished from ketones?

A

they can be distinguished as aldehydes can be oxidised whereas ketones cannot

91
Q

what happens during the oxidation and reduction of an aldehyde?

A

during oxidation the O:H ratio increases.

during reduction the O:H ratio decreases

92
Q

what does the oxidation of edible oils produce?

A

the oxidation of edible oils produces a rancid taste

93
Q

rancid meaning?

A

the term used to describe the taste of the oxidation products of edible oils

94
Q

what are antioxidants?

A

they are compounds that are added to prevent oxidation. the compound itself is easily oxidised and so protects other molecules from oxidation. they are made of molecules that are oxidised easily

95
Q

how to name aldehydes and ketones?

A

aldehydes and ketones contain the carboxyl group (-C=O), which is at the end of the chain in aldehydes and anywhere expect the end in ketones

96
Q

what are essential oils used in?

A
  • cleaning products
  • flavourings
  • cosmetics and perfumes
97
Q

where are essential oils found?

A

Essential oils are concentrated extracts of aroma compounds from plants that are not water-soluble. They are volatile and have distinctive smells.

98
Q

what are essential oils made of?

A

While they contain a mixture of organic compounds, one of the primary constituents of essential oils are terpenes.

99
Q

what is the structural name of isoprene?

A

2-methylbuta-1,3-diene.

100
Q

what are isoprene used for?

A

These unsaturated C5H8 units can add together head to tail to form terpenes. Both long, straight-chain molecules or cyclic molecules can be formed.

101
Q

how is the number of isoprene units in a terpene calculated?

A

they are calculated by counting the total number of carbon atoms and dividing by 5.

102
Q

define terpene?

A

an unsaturated compound in many plant oils. terpenes are formed by joining isoprene units together

103
Q

what are free radicals?

A

highly reactive atoms or molecules with unpaired electrons. . They are unstable as there is a tendency for unpaired electrons to pair up and so the free radicals react very quickly.

104
Q

initiation meaning?

A

the start of a free radical chain reaction. involves the breaking of a covalent bond to form free radicals that react with a molecule to produce another free radical.

105
Q

propagation meaning?

A

the second stage is a free radical chain reaction. The highly reactive radicals formed can remove atoms from other (stable) compounds to re-establish stable covalent bonds. This reaction will produce a new free radical.

106
Q

termination meaning?

A

the final stage in a free-radical chain reaction in which two free radicals combine to form a stable molecule

107
Q

What’s is ultraviolet light?

A

Ultraviolet radiation (UV) from the sun is a high energy form of light.

108
Q

how are free radicals formed?

A

Radicals can be formed when a covalent bond is broken by energy supplied by UV light. Due to their reactivity, they are able to cause chain reactions, as they often react to produce other free radicals. These reactions happen in a three stage process.

109
Q

which stages of the free radical process require energy?

A

While UV light is needed to begin the process, further reactions do not need UV light, and so the chain reaction can continue, even in total darkness.

110
Q

formulas for saturated and unsaturated fatty acids?

A

CnH2nO2 = saturated
less than CnH2nO2 = unsaturated

for each extra double bond is an extra-2

111
Q

how can you tell if a fatty acid is monounsaturated or polyunsaturated?

A 
monounsaturated =  CnH2n-2
polyunsaturated = CnH2n-(>2)

Each extra double bond is an extra-2

112
Q

what are free radical scavengers?

A

Free radical scavengers are chemicals (usually an antioxidant) that react with and destroy free radicals. This is often desirable to help protect our skin and our food.

113
Q

what are free-radical scavengers an example of?

A

Many free radical scavengers are antioxidants.

114
Q

what does more saturation mean in fats and oils ?

A

higher melting/boiling points due to closer packing of molecules

115
Q

neutralisation of metal hydroxide with acid

A

metalOH + acid —-> Metal+Acid (minus hydrogen)

116
Q

neutralisation of metal carbonate

A

metalCO3 + acid —> Salt + CO2 + H2O

117
Q

what is the neutralisation of metal oxides?

A

metal-oxide + acid —-> salt + water

118
Q

how to name salts in neutralisation?

A

metal + non-metal ion

Higher Chemistry (3 decks)

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