Unit 2 - Nature's Chemistry

Question 1

What is the functional group for an ester

Answer 1

Ester link

Question 2

What does an ester’s name end in

Answer 2

-yl -oate

Question 3

How are esters made

Answer 3

Condensation or esterification reaction

Question 4

What is the word equation for esterification

Answer 4

Alcohol + carboxylic acid ester + water

Question 5

Why is a wet paper towel used in a condensation reaction

Answer 5

To catch any gases that escape from the reaction

Question 6

What is the catalyst used in a condensation reaction

Answer 6

Concentrated sulphuric acid

Question 7

What is used to heat the reactants during a condensation reaction

Answer 7

Hot water bath - since alcohol flammable

Question 8

How can you tell if an ester has been produced

Answer 8

Oily layer and a sweet smell

Question 9

Why is sodium hydroxide used in a condensation reaction

Answer 9

To neutralise the acid catalyst

Question 10

What are some uses for esters

Answer 10

• fragrances
• flavourings
• nail polish
• solvents for car paint

Question 11

What is hydrolysis

Answer 11

The breaking up of a substance using water

Question 12

What are fats and oils example of

Answer 12

Esters

Question 13

Why do we need fats and oils

Answer 13

Give our body energy

Question 14

Is a fat saturated or unsaturated

Answer 14

Saturated (c-c singles bonds)

Question 15

Why do fats have higher melting points than oils

Answer 15

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

Question 16

Will a fat decolourise bromine solution

Answer 16

No it is a saturated molecule

Question 17

Is an oil saturated or unsaturated?

Answer 17

Unsaturated (c=c double bonds)

Question 18

Will an oil decolourise bromine solution

Answer 18

Yes - unsaturated molecule

Question 19

What happens when oils react with oxygen

Answer 19

Turns rancid

Question 20

What is the chemical reaction used to produce fats and oils

Answer 20

Condensation/ esterification

Question 21

What molecules are needed to make a fat/oil

Answer 21

Glycerol + 3 fatty acids

Question 22

What is hydrogenation

Answer 22

The addition of hydrogen to an unsaturated molecule

Question 23

How is an alkane produced

Answer 23

When an alkene is reacted with hydrogen in a hydrogenation reaction

Question 24

What happens when an oil reacts with hydrogen

Answer 24

Turns into margarine (hardening)

Question 25

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

Answer 25

Essential amino acid

Question 26

What type of link is found in proteins

Answer 26

Amide/peptide link

Question 27

What type of reaction is used to form proteins

Answer 27

Condensation

Question 28

What are proteins made from

Answer 28

Amino acids

Question 29

What produces amino acids during digestion

Answer 29

Enzyme hydrolysis of dietary proteins

Question 30

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

Answer 30

Hydrolysis

Question 31

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

Answer 31

Carbon with double bonded oxygen and nitrogen

Question 32

What are the two types of protein structure

Answer 32

Fibrous and globular

Question 33

What is the structure of a fibrous protein

Answer 33

Polypeptide chains interwoven, held together by hydrogen bonds

Question 34

What kind of properties do fibrous proteins have

Answer 34

Toughness, insolubility, resistance to changes in pH

Question 35

What is the structure of globular proteins

Answer 35

Polypeptide chains are coiled together in spherical shapes

Question 36

What happens to the structure of a protein when heated

Answer 36

Structure changes (eg heating an egg)

Question 37

What happens to polarity and flammability as the carbon chain increases

Answer 37

Both decrease

Question 38

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

Answer 38

There is less hydrogen bonding between molecules

Question 39

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

Answer 39

Three hydroxyl groups

Question 40

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

Answer 40

- higher boiling points - increased viscosity - increased solubility in water

Question 41

What makes an alcohol primary

Answer 41

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

Question 42

What makes an alcohol secondary

Answer 42

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

Question 43

What makes an alcohol tertiary

Answer 43

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

Question 44

What type(s) of alcohols oxidise

Answer 44

Primary and secondary

Question 45

How do you know when an alcohol has been oxidised

Answer 45

The oxygen to hydrogen ratio increases

Question 46

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

Answer 46

Orange to green

Question 47

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

Answer 47

Black solid to brown solid

Question 48

Where is the functional group of an aldehyde

Answer 48

End of molecule

Question 49

When naming an aldehyde what does it end in

Answer 49

-al

Question 50

When naming a ketone what does it end in

Answer 50

-one

Question 51

Where is the functional group in a kentone

Answer 51

Middle of a molecule

Question 52

Which oxidises, an aldehyde or a ketone

Answer 52

Aldehyde

Question 53

What does a primary alcohol oxidise into

Answer 53

Aldehyde

Question 54

What does a secondary alcohol oxidise into

Answer 54

Ketone

Question 55

What does an aldehyde oxidise into

Answer 55

Carboxylic acid

Question 56

Name 3 oxidising agents

Answer 56

- acidified potassium dichromate - fehlings solution - tollen's reagent

Question 57

What is the colour change for fehling's solution

Answer 57

Blue to orange/red

Question 58

What oxidising agent forms a silver mirror when oxidised

Answer 58

Tollen's reagent

Question 59

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

Answer 59

O:H ratio decreases

Question 60

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

Answer 60

Water

Question 61

What can be used for a neutralisation reaction

Answer 61

Titration

Question 62

What are antioxidants

Answer 62

Molecules which can prevent oxidation reactions taking place

Question 63

Why are antioxidants good reducing agents

Answer 63

Oxidises itself so that it can prevent other compounds from oxidation

Question 64

Give an example of a common antioxidant

Answer 64

Vitamin C

Question 65

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

Answer 65

- volatility - boiling point - solubility - heating proteins - oxidation

Question 66

What is volatility

Answer 66

How easily food vaporises

Question 67

Do flavour molecules have strong or weak intermolecular forces

Answer 67

Weak

Question 68

When a molecule water soluble

Answer 68

If the functional group can hydrogen bond with water

Question 69

When is a molecule oil soluble

Answer 69

If the functional group cannot hydrogen bond with water

Question 70

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

Answer 70

Oil

Question 71

What happens when a protein is heated

Answer 71

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

Question 72

What are salts of fatty acids

Answer 72

Soaps

Question 73

How are soaps formed

Answer 73

Alkaline hydrolysis of fats/oils

Question 74

What reactions/molecules are involved in alkaline hydrolysis

Answer 74

Fat/oil -hydrolysis-> glycerol + fatty acids | Fatty acids + sodium hydroxide - neutralisation-> soap + water

Question 75

What part of the soap structure is non-polar

Answer 75

Covalent hydrocarbon chain (tail)

Question 76

What part of the soap molecule is hydrophilic

Answer 76

Carboxylate head

Question 77

Is the carboxylate head polar or non-polar

Answer 77

Polar

Question 78

What part of the soap molecule is hydrophobic

Answer 78

Covalent hydrocarbon chain (tail)

Question 79

What results in an emulsion being formed

Answer 79

The repulsion of negative charges

Question 80

After agitation of the soap and grease molecules what are formed

Answer 80

Micelles

Question 81

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

Answer 81

The hydrocarbon tail

Question 82

Define an emulsion

Answer 82

Small droplets of one liquid dispersed in another liquid

Question 83

Name some examples of emulsions

Answer 83

- mayonnaise - milk - butter - margarine

Question 84

What can be added to prevent oil and water components separating

Answer 84

Emulsifier

Question 85

How is an emulsifier formed

Answer 85

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

Question 86

What are essential oils

Answer 86

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

Question 87

What are some common uses of essential oils

Answer 87

- perfumes - cosmetic products - cleaning products - flavourings in food

Question 88

What are key compounds in essential oils

Answer 88

Terpenes

Question 89

How are essential oils extracted

Answer 89

Steam distillation

Question 90

What are terpenes

Answer 90

Unsaturated compounds formed by joining isoprene units together

Question 91

What is the systematic name for an isoprene unit

Answer 91

2-methylbuta-1,3-diene

Question 92

How many carbons are present in an isoprene unit

Answer 92

5 carbons

Question 93

Draw an isoprene unit

Answer 93

(See notes)

Question 94

What does a terpene form when it is oxidised

Answer 94

Terpenoids

Question 95

What do terpenoids contain

Answer 95

Hydroxyl or carbonyl functional group

Question 96

When UV light breaks bonds what are formed

Answer 96

Free radicals

Question 97

What are free radicals

Answer 97

Highly reactive unpaired electrons

Question 98

What are the 3 steps in a free radical chain reaction

Answer 98

- initiation - propagation - termination

Question 99

How does the chain reaction stop during termination

Answer 99

Stable molecules formed

Question 100

What are free radical scavengers

Answer 100

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

Question 101

What are free radical scavengers often found in

Answer 101

Cosmetic products (eg sun cream)