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Higher Chemistry > Jotter 3 > Flashcards

Jotter 3 Flashcards

(72 cards)

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1
Q

What is a condensation polymer?

A

A polymer whose polymerisation involves a condensation reaction.

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2
Q

What can be done to condensation polymers to get their monomers?

A

They can be hydrolysed meaning their reaction can be reversed.

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3
Q

How does the hydrolysis of proteins occur?

A

Hydrolysis of proteins is conducted in a lab by heating with a fairly concentrated hydrochloride acid under reflux.

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4
Q

What forces are proteins held by to be able to maintain their shapes?

A

Intermolecular forces (hydrogen bonding).

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5
Q

What do enzyme name usually end in?

A

-ase.

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6
Q

What happens to peptide links when tissue is heated up?

A

The peptide links remain intact although the shape of the enzyme molecule becomes irreversibly denatured.

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7
Q

What might some foods contain that puts them at the greatest risk of oxidation?

A

Fats or oils.

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8
Q

What must be added to foods even if they contain the smallest bit of oil or fat?

A

Antioxidants.

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9
Q

Where are antioxidants commonly used?

A

They are commonly used in products like, vegetable oil, animal fat, meat, fish, poultry, dairy products, mayonnaise, potato products, etc.

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10
Q

What methods do food manufacturers use to prevent oxidation?

A

Packaging the foods in an atmosphere of nitrogen or adding an antioxidant such as Vitamin C.

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11
Q

What happens to fats when they react with oxygen?

A

The fats are being broken down which causes, loss of colour, loss of nutritional value, deterioration of flavour and even a health risk due to toxic oxidation products.

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12
Q

What chemicals are produced when fat reacts with oxygen?

A

Chemicals called peroxides are produced which causes the flavour and smell to deteriorate which means peroxides are what give meat that rancid smell and flavour.

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13
Q

What do antioxidants do?

A

They prevent the formation of peroxides meaning they slow down the process of food going off.

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14
Q

What can oxidation reactions produce?

A

Free radicals.

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15
Q

What is a free radical?

A

It is a highly reactive species that contains an unpaired electron.

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16
Q

How do free radicals damage food?

A

They damage food by the removal of an electron.

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17
Q

How do antioxidants act on free radicals?

A

They act by transferring one of their electrons to the free radical which neutralises it by forming a stable pair of electrons within the free radical.

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18
Q

What happens to the antioxidants when they give away one of their electrons?

A

They turn into a stable species of free radical.

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19
Q

What can Vitamin C (ascorbic acid) act as?

A

It can can act as a reducing agent which prevents oxidation.

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20
Q

What does Melatonin do as a hormone?

A

It regulates sleep in our bodies.

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21
Q

What are some examples of antioxidants?

A

Melatonin, regulates sleep

Vitamin C, found in nuts

α-tocopherol (Vitamin E), found in nuts

β-carotene (Vitamin A), found in carrots, can improve tan

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22
Q

What are many of the flavour and aroma molecules?

A

They are aldehydes which can be oxidised.

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23
Q

What molecules contribute to flavour?

A

Molecules which are volatile.

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24
Q

What are some of the properties of volatile molecules?

A

They have low molecular mass- less than 300 (low boiling point)

They have London dispersion forces as their intermolecular force making them have a low boiling point

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25
How can the volatility and boiling point of a compound be predicted?
The presence of O-H or N-H bonds that will cause hydrogen bonding and will make it soluble in water (polar) The arrangement of polar covalent bonds which can result in dipole:dipole forces which increases boiling point meaning it affects volatility Molecular size, which may affect the size of LDFs increasing the boiling point (affecting volatility) The polarities of the solute and the solvent which affects solubility
26
What is the most important feature in cooking food?
Whether the functional groups that are present are water soluble or not as if they are it means they can form hydrogen bonding with water but if they can’t that means they are oil soluble (like dissolves like).
27
What is an important feature of cooking that involves the method and time?
Method and times are important in cooking food as if done right it preserves the flavour as some flavour molecule might dissolve in the cooking liquid and lost if done wrong.
28
How is flavour in food preserved when using water?
Water is used to cook foods which contain oil soluble flavours such as, green beans or broccoli.
29
How is flavour in food preserved when using oil?
Oil is used to cook foods which contain water-soluble flavours such as, asparagus.
30
What do the functional groups that are present within the flavour molecule determine?
They determine the type of intermolecular forces present. With a hydroxyl group meaning it has hydrogen bonding and is polar as it is water soluble.
31
What are essential oils?
They are non-water-soluble, volatile liquids that are extracted from plant material.
32
What are some distinctive fragrances?
Lavender, Peppermint, Orange, Lemon and Eucalyptus.
33
What is difficult about extracting oils from plants?
It is obtaining them before they evaporate.
34
What happens to oil during steam distillation?
The oil is carried by the steam to a condenser.
35
Where are essential oils used?
They are used in perfumes, cosmetics and cleaning products such as soap.
36
What are the key components in essential oils?
Terpenes.
37
What aroma do terpenes from plants produce when oxidised?
They produce a spice aroma.
38
What is the ester that is found in the essential oil of lavender?
Linalyl Acetate
39
What is an ester that is commonly added to perfumes?
Linalyl Acetate.
40
What terpene does the essential oil ‘lemon oil’ contain?
It contains d-limonene which can be used as a natural solvent or cleanser.
41
What essential oil is commonly added to cosmetics and what is its function?
Geraniol, it is added to balance and revitalise the skin.
42
What types of flavours and aromas are terpenes known for?
Fruity and floral.
43
Are Terpenes saturated compounds?
No, they are unsaturated compounds.
44
What are terpenes built up from?
They are built up from units of isoprene.
45
Why are terpenes always unsaturated?
This is because they have a C=C meaning they oxidise easily.
46
What is isoprene in terms of structure?
It always contains 5 carbons and has a molecular formula of C₅H₈.
47
What are terpenes called when they include oxygen atoms?
Terpenoids.
48
As terpenes are built up from isoprene units that are joined together what formula do they have?
(C₅H₈)n where n in the number of linked isoprene units.
49
What are the different ways that isoprene units can be linked?
They can be linked head to tail in order to form linear terpenes They can be linked in rings to form cyclic terpenes
50
What is an example of a linear terpene?
Myrcene.
51
What is Myrcene a component of?
It is a component of plants such as, bay, ylang-ylang and thyme.
52
What is an example of a cyclic terpene?
Limonene (peel of citrus fruits)
53
What is an example of a cyclic terpenoid?
Menthol (peppermint)
54
What is the function of sunscreen/sun cream?
It’s is used to prevent harmful damage to the skin from the UV radiation from the sun as it absorbs the rays.
55
What can overexposure to UVB cause?
It can cause problems such as sunburn or in extreme cases even skin cancer.
56
How many types of UV radiation are there?
3, UVA, UVB and UVC.
57
What are the 2 types of chemicals that are used to protect us from the sun?
Sunblock and sunscreen.
58
What is the function of sunblock?
As sunblocks contain chemicals such as titanium dioxide, they reflect the UV radiation.
59
What is the function of sunscreens?
They contain chemicals which absorb the UV radiation.
60
How has UVA radiation been found to be dangerous in recent studies?
It was seen that UVA contributes to skin cancer as it indirectly breaks down DNA in a process that involves free radicals.
61
What do all 3 types of UV radiation do?
They all affect the breakdown of collagen in our skin which lead to premature aging.
62
What ultraviolet (UV) radiation?
Ultraviolet radiation is a high energy form of light from the sun that has 3 main types which go in order of increasing energy, UVA, UVB and UVC.
63
How can radicals be formed?
Radicals can be formed when a covalent bond is broken by energy supplied by UV light.
64
Why do free radicals react very quickly?
This is due to the fact that they have an unpaired electron and react very quickly in order to become stable.
65
What can happen due to the quick reactivity of free radicals?
They can cause chain reactions as they often react to produce other free radicals.
66
What 3 stages do chain reactions have?
1. Initiation- when energy from the UV light breaks the Cl-Cl covalent bonds forming 2 free radicals. 2. Propagation- the reactive free radicals react with hydrogen producing more free radicals. 3. Termination- free radicals react with each other forming stable molecules.
67
What are halogen highly susceptible to?
UV radiation that breaks them into free radicals, this is how the photochemical reaction between an alkane and bromine works.
68
What does the ‘.’ represent?
It represents the unpaired electron.
69
How long does Propagation take place?
Until one of the reactants are used up.
70
Why are some chemicals stored in brown glass bottles?
They filter out the light as some chemical (such as halogens) are very susceptible to UV radiation.
71
What are free radical scavengers?
They are chemicals (usually vitamins, enzymes or minerals) that react with and destroy free radicals.
72
What are free radical scavengers most commonly seen as?
Antioxidants.

Higher Chemistry (3 decks)

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