Unit 2 - Nature's Chemistry Flashcards

1
Q

What is the functional group for an ester

A

Ester link

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2
Q

What does an ester’s name end in

A

-yl -oate

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3
Q

How are esters made

A

Condensation or esterification reaction

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4
Q

What is the word equation for esterification

A

Alcohol + carboxylic acid ester + water

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5
Q

Why is a wet paper towel used in a condensation reaction

A

To catch any gases that escape from the reaction

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6
Q

What is the catalyst used in a condensation reaction

A

Concentrated sulphuric acid

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7
Q

What is used to heat the reactants during a condensation reaction

A

Hot water bath - since alcohol flammable

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8
Q

How can you tell if an ester has been produced

A

Oily layer and a sweet smell

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9
Q

Why is sodium hydroxide used in a condensation reaction

A

To neutralise the acid catalyst

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10
Q

What are some uses for esters

A
  • fragrances
  • flavourings
  • nail polish
  • solvents for car paint
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11
Q

What is hydrolysis

A

The breaking up of a substance using water

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12
Q

What are fats and oils example of

A

Esters

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13
Q

Why do we need fats and oils

A

Give our body energy

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14
Q

Is a fat saturated or unsaturated

A

Saturated (c-c singles bonds)

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15
Q

Why do fats have higher melting points than oils

A

Molecules pack closer together, stronger Van Der Waal forces between them, higher melting points

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16
Q

Will a fat decolourise bromine solution

A

No it is a saturated molecule

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17
Q

Is an oil saturated or unsaturated?

A

Unsaturated (c=c double bonds)

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18
Q

Will an oil decolourise bromine solution

A

Yes - unsaturated molecule

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19
Q

What happens when oils react with oxygen

A

Turns rancid

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20
Q

What is the chemical reaction used to produce fats and oils

A

Condensation/ esterification

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21
Q

What molecules are needed to make a fat/oil

A

Glycerol + 3 fatty acids

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22
Q

What is hydrogenation

A

The addition of hydrogen to an unsaturated molecule

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23
Q

How is an alkane produced

A

When an alkene is reacted with hydrogen in a hydrogenation reaction

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24
Q

What happens when an oil reacts with hydrogen

A

Turns into margarine (hardening)

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25
Q

What term is used to describe an amino acid that must be obtained from our diet

A

Essential amino acid

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26
Q

What type of link is found in proteins

A

Amide/peptide link

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27
Q

What type of reaction is used to form proteins

A

Condensation

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28
Q

What are proteins made from

A

Amino acids

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29
Q

What produces amino acids during digestion

A

Enzyme hydrolysis of dietary proteins

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30
Q

What type of reaction is used to break down proteins to form amino acids

A

Hydrolysis

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31
Q

Between what elements in the protein do the bonds break between during hydrolysis

A

Carbon with double bonded oxygen and nitrogen

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32
Q

What are the two types of protein structure

A

Fibrous and globular

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33
Q

What is the structure of a fibrous protein

A

Polypeptide chains interwoven, held together by hydrogen bonds

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34
Q

What kind of properties do fibrous proteins have

A

Toughness, insolubility, resistance to changes in pH

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35
Q

What is the structure of globular proteins

A

Polypeptide chains are coiled together in spherical shapes

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36
Q

What happens to the structure of a protein when heated

A

Structure changes (eg heating an egg)

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37
Q

What happens to polarity and flammability as the carbon chain increases

A

Both decrease

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38
Q

Why does polarity and flammability decrease as the carbon chain increases?

A

There is less hydrogen bonding between molecules

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39
Q

If an alcohol ends in -triol how many hydroxyl groups are present

A

Three hydroxyl groups

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40
Q

What happens to the properties of a molecule as there is an increase in hydrogen bonding

A
  • higher boiling points
  • increased viscosity
  • increased solubility in water
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41
Q

What makes an alcohol primary

A

The carbon that is attached to the hydroxyl group is surrounded by 1 other carbon

42
Q

What makes an alcohol secondary

A

The carbon attached to the hydroxyl group is surrounded by 2 carbons

43
Q

What makes an alcohol tertiary

A

The carbon attached to the hydroxyl group is surrounded by 3 carbons

44
Q

What type(s) of alcohols oxidise

A

Primary and secondary

45
Q

How do you know when an alcohol has been oxidised

A

The oxygen to hydrogen ratio increases

46
Q

What is the colour change when an alcohol is oxidised using acidified potassium dichromate

A

Orange to green

47
Q

What is the colour change when an alcohol is oxidised using copper dioxide

A

Black solid to brown solid

48
Q

Where is the functional group of an aldehyde

A

End of molecule

49
Q

When naming an aldehyde what does it end in

A

-al

50
Q

When naming a ketone what does it end in

A

-one

51
Q

Where is the functional group in a kentone

A

Middle of a molecule

52
Q

Which oxidises, an aldehyde or a ketone

A

Aldehyde

53
Q

What does a primary alcohol oxidise into

A

Aldehyde

54
Q

What does a secondary alcohol oxidise into

A

Ketone

55
Q

What does an aldehyde oxidise into

A

Carboxylic acid

56
Q

Name 3 oxidising agents

A
  • acidified potassium dichromate
  • fehlings solution
  • tollen’s reagent
57
Q

What is the colour change for fehling’s solution

A

Blue to orange/red

58
Q

What oxidising agent forms a silver mirror when oxidised

A

Tollen’s reagent

59
Q

What happens to the oxygen to hydrogen ratio in a reduction reaction

A

O:H ratio decreases

60
Q

In a neutralisation reaction what is produced as a by-product

A

Water

61
Q

What can be used for a neutralisation reaction

A

Titration

62
Q

What are antioxidants

A

Molecules which can prevent oxidation reactions taking place

63
Q

Why are antioxidants good reducing agents

A

Oxidises itself so that it can prevent other compounds from oxidation

64
Q

Give an example of a common antioxidant

A

Vitamin C

65
Q

When answering a question on “chemistry of cooking” what are some factors to consider

A
  • volatility
  • boiling point
  • solubility
  • heating proteins
  • oxidation
66
Q

What is volatility

A

How easily food vaporises

67
Q

Do flavour molecules have strong or weak intermolecular forces

A

Weak

68
Q

When a molecule water soluble

A

If the functional group can hydrogen bond with water

69
Q

When is a molecule oil soluble

A

If the functional group cannot hydrogen bond with water

70
Q

What is a molecule with a long hydrocarbon chain most likely to be soluble in

A

Oil

71
Q

What happens when a protein is heated

A

Intermolecular forces broken, changes shape (denatures), alters texture

72
Q

What are salts of fatty acids

A

Soaps

73
Q

How are soaps formed

A

Alkaline hydrolysis of fats/oils

74
Q

What reactions/molecules are involved in alkaline hydrolysis

A

Fat/oil -hydrolysis-> glycerol + fatty acids

Fatty acids + sodium hydroxide - neutralisation-> soap + water

75
Q

What part of the soap structure is non-polar

A

Covalent hydrocarbon chain (tail)

76
Q

What part of the soap molecule is hydrophilic

A

Carboxylate head

77
Q

Is the carboxylate head polar or non-polar

A

Polar

78
Q

What part of the soap molecule is hydrophobic

A

Covalent hydrocarbon chain (tail)

79
Q

What results in an emulsion being formed

A

The repulsion of negative charges

80
Q

After agitation of the soap and grease molecules what are formed

A

Micelles

81
Q

During the cleansing action of soap what part of the soap molecule attaches to the grease

A

The hydrocarbon tail

82
Q

Define an emulsion

A

Small droplets of one liquid dispersed in another liquid

83
Q

Name some examples of emulsions

A
  • mayonnaise
  • milk
  • butter
  • margarine
84
Q

What can be added to prevent oil and water components separating

A

Emulsifier

85
Q

How is an emulsifier formed

A

By reacting glycerol and 2 fatty acids together in a condensation reaction

86
Q

What are essential oils

A

Concentrated extracts of the volatile non-water soluble aroma compounds from plants

87
Q

What are some common uses of essential oils

A
  • perfumes
  • cosmetic products
  • cleaning products
  • flavourings in food
88
Q

What are key compounds in essential oils

A

Terpenes

89
Q

How are essential oils extracted

A

Steam distillation

90
Q

What are terpenes

A

Unsaturated compounds formed by joining isoprene units together

91
Q

What is the systematic name for an isoprene unit

A

2-methylbuta-1,3-diene

92
Q

How many carbons are present in an isoprene unit

A

5 carbons

93
Q

Draw an isoprene unit

A

(See notes)

94
Q

What does a terpene form when it is oxidised

A

Terpenoids

95
Q

What do terpenoids contain

A

Hydroxyl or carbonyl functional group

96
Q

When UV light breaks bonds what are formed

A

Free radicals

97
Q

What are free radicals

A

Highly reactive unpaired electrons

98
Q

What are the 3 steps in a free radical chain reaction

A
  • initiation
  • propagation
  • termination
99
Q

How does the chain reaction stop during termination

A

Stable molecules formed

100
Q

What are free radical scavengers

A

Molecules which can react with free radicals and form stable product to prevent chain reactions

101
Q

What are free radical scavengers often found in

A

Cosmetic products (eg sun cream)