Unit 3- Natures Chemistry Flashcards
1
Q
how would you identify a secondary alcohol?
A
the hydroxyl functional group is on a carbon inside the molecule.
eg. butan-2-ol or pentan-3-ol
2
Q
how would you identify a tertiary alcohol?
A
the hydroxyl functional group is on the same carbon as a branch.
eg. 2-methylbutan-1-ol or 3-methylpentan-3-ol
3
Q
describe the oxidation of a primary alcohol.
A
primary alcohol -> aldehyde -> carboxylic acid
4
Q
describe the oxidation of butan-1-ol
A
butan-1-ol -> butanal -> butanoic acid
5
Q
describe the oxidation of pentan-2-ol
A
pentan-2-ol -> pentan-2-one
6
Q
describe the oxidation of a tertiary alcohol
A
tertiary alcohols do not oxidise
7
Q
what is the functional group and its placement in a ketone?
A
carbonyl inside the carbon
8
Q
in what way is food packaged to help prevent it oxidising and spoiling?
A
packaged in an inert gas like nitrogen that will not react with the food.
9
Q
what is the colour change when reacting acidified potassium dichromate with an aldehyde?
A
orange to green
10
Q
what are free radical scavengers?
A
molecules that can react with free radicals to form stable molecules and prevent chain reactions
11
Q
what is the colour change when reacting fehlings solution with an aldehyde?
A
blue to a brick red precipitate
12
Q
how are soaps made?
A
the alkaline hydrolysis of fats and oils.
13
Q
in a termination reaction where are the free radicals?
A
on the reaction side only of the equation
14
Q
what is the colour change when reacting an aldehyde with tollens reagent?
A
clear to a silver mirror
15
Q
why will a ketone not react with an oxidising agent?
A
because ketones cannot be oxidised any further.
16
Q
what is an emulsion?
A
when droplets of one liquid are suspended in another liquid.
17
Q
what is an example of an emulsion?
A
a mixture of oil and water.
18
Q
explain what is meant by an emulsifier
A
a soap like molecule used to prevent oil and water components from separating
19
Q
how are emulsifiers made?
A
reacting edible oils with glycerol
20
Q
what are three amino acids joined together called?
A
a tripeptide
21
Q
how do emulsifiers differ from fats and oils?
A
fats and oils have 3 fatty acid chains linked to the glycerol backbone whereas emulsifiers have one or 2
22
Q
explain how emulsifiers work
A
the one or 2 hydroxyl groups are hydrophillic and the fatty acid chains are hydrophobic
23
Q
what is the functional group present in esters?
A
ester link
24
Q
what is the reverse reaction of esterification/condensation
A
hydrolysis
25
what is a condensation reaction?
when 2 or more small molecules join to form a larger molecule and releases water.
26
what are terpenes?
the key components in most essential oils
27
what is the word equation for the formation of an ester?
carboxylic acid+alcohol -> ester+water
28
what would be the result of esterification of ethanoic acid and methanol?
methyl ethanoate and water
29
how do you name esters?
first part comes from the alcohol e.g. methanol = methyl
the second part comes from the carboxylic acid e.g. methanoic acid = methanoate
30
in an experiment how would you know if an ester has been made?
the mixture fizzes
oily drops on the surface (ester)
sweet smell
31
how are ester broken?
by hydrolysis
in the lab an alkali is normally used then distillation can be used to separate the alcohol from the acid.
32
describe the relationship between fats and c-c single bonds
fats contain c-c bonds so:
they pack closely together
they have strong van der waals forces
they have higher melting points
33
what are some uses for esters?
flavourings for foods
perfumes
solvents for other non polar molecules
34
what are the physical properties of esters?
insoluble/immiscible in water
sweet smelling
volatile
35
what is the relationship of boiling points of esters and mass
boiling points increases as mass increases
36
what is the back bone of fats and oils known as?
glycerol
37
how does oxidation of unsaturated oils and fats take place?
via a free-radical mediated process
38
what is the systematic name for glycerol?
propan-1,2,3-triol
39
how would you identify a primary alcohol?
the hydroxyl functional group is on the end carbon
eg, propan-1-ol or butan-1-ol
39
what is the functional group and its placement in an aldehyde?
carbonyl on an end carbon
39
what are fatty acids?
carboxylic acids containing EVEN numbers of carbon atoms
42
what does saturated mean?
only single bonds
43
what does unsaturated mean?
several c=c
44
what is the molar ratio of glycerol to fatty acids in dats and oils?
1:3
45
saturated tail
hydrogen atoms are more than 2x the carbon atoms specifically within the long chain beyond the ester link
46
unsaturated tail
hydrogen atoms are less than 2x the carbon atoms specifically within the long chain beyond the ester link
47
in fats and oils which contain saturated tails and which contain unsaturated tails?
fats contain saturated tails and oils contain unsaturated tails
48
what are the products of the hydrolysis of a triglyceride?
one mole of glycerol and 3 moles of fatty acids
49
what state are fats and oils in at room temperature?
fats are solid
| oils are liquid
50
why causes oils to be liquid at room temperature?
due to the high proportion of unsaturated molecules and small amount of intermolecular forces.
51
describe the relationship between oils and c=c bonds
oils contain c=c bonds so:
they dont pack as closely together as the double bond creates a kink
they have weaker van der waals forces
they have lower melting points
52
what is the systematic name of an isoprene unit?
2-methylbuta-1,3-diene
53
in a propagation reaction where are the free radicals?
on both the reactant and product side of the equation
54
what is a hydrolysis reaction?
breaking down of larger molecules into smaller molecules by reaction with water
54
why are oils thought to be healthier?
theyre less likely to be deposited in our arteries
55
give an example of something that would hydrolyse a fat or oil into a salt
potassium hydroxide or sodium hydroxide
56
describe the oxidation of a secondary alcohol
secondary alcohol -> ketone
56
what are the requirements to make esters in an experiment?
Step 1
```
alcohol
carboxylic acid
concentrated sulfuric acid (catalyst)
hot water bath
test tube
cold wet paper towel
cotton wool bung
```
Step 2
mix with sodium hydrogen carbonate
57
by what process are oils 'hardened'
hydrogenation
57
describe the structure of a soap molecule
non polar tail and a polar ionic head
58
describe how a soap molecule interacts with water
non-polar tail is hydrophobic and is repelled by water
polar, ionic head is hydrophillic and dissolves in polar solvents like water
58
describe how soaps clean
hydrophobic tail of the molecule dissolves in the oil or grease droplet
hydrophillic head dissolves in the surrounding water
once scrubbed properly the grease is broken up into droplets and suspended in the water ready to be washed away
60
what are soaps?
salts made from the alkaline hydrolysis of fats and oils
62
what are antioxidants?
antioxidants are molecules that reduce the rate of oxidation reactions involving the transfer of electron(s) to an oxidising agent.
63
how do antioxidants work?
antioxidant molecules donate an electron to the free radical, becoming oxidised in the process .
64
what are the 4 elements that all proteins contain?
carbon
hydrogen
oxygen
nitrogen
65
what are proteins?
condensation polymers made by linking amino acids together
66
when does oxidation of food occur?
when food is exposed to oxygen in the air. particularly foods containing fats and oils.
67
describe the process of hydrogenation of oils?
oils can be converted into 'hardened' fats by the addition of hydrogen known as hydrogenation, using a nickel catalyst.
this involves the partial removal of the unsaturation (removal of SOME of the c=c)
turns the oil into a more saturated fat and allows it to pack more closely together.
67
why are fats and oils vital in the body?
they provide us with energy and are vital for the transport of vitamins around the body.
67
what are essential amino acids?
amino acids that must be maintained by the diet that the body cannot make itself
74
how do you how do you extract essential oils?
steam distillation
75
when mixed with an oxidising agent which will react?
Aldehyde or ketone?
Aldehyde
75
what are many amino acids joined together called?
a polypeptide
76
what functional groups are present in amino acids?
the amine group (NH2) and the carboxyl group (COOH)
77
what is the name of the process used to make proteins?
condensation polymerisation
78
what are two amino acids joined together called?
a dipeptide
79
what is an example of an ester?
fats and oils
81
What are the three types of alcohol?
primary
secondary
tertiary
82
Why do we need proteins in our diet?
for growth and repair of tissues
83
describe what happens when we eat proteins in our body
enzymes break the protein down by hydrolysis into amino acids
the amino acids are transported by the blood
in the blood stream condensation reactions occur to build up the amino acids into proteins required in the body
84
what are the two types of protein?
fibrous and globular
85
what are fibrous proteins?
the major structural material of animal tissue and found in animal hair, nails and muscle
86
describe the shape and solubility of fibrous proteins
they have their long spiral chains folded into long thin shapes and are generally insoluble in water
86
what are globular proteins?
molecules involved in regulation of life processes
| like haemoglobin, hormones and enzymes
86
describe the shape and solubility of globular proteins
they have their spiral chains folded into spherical shapes and are generally soluble in water
86
what type of van der waals force do proteins experience?
hydrogen bonding
88
what are detergents?
a family of compounds that are similar to soaps and work in a similar way. They are most commonly used in areas where hard water is present.
90
give an example of a globular protein
insulin or haemoglobin
91
how many fatty acids must react with glycerol to form the fat/oil?
3
93
what does exposure to UV light cause?
it results in molecules gaining enough energy for bonds to be broken. leading to sun burn and premature ageing
94
explain why proteins experience hydrogen bonding
due to their polar CO and NH groups of the amide link
95
what are enzymes?
proteins which act as biological catalysts
96
what are terpenes built from?
isoprene units
97
are terpenes saturated or unsaturated?
unsaturated
98
explain how the protein in egg whites are a good example of denaturing
the protein in egg whites are an example of a globular protein held together by hydrogen bonding
when heat is applied the energy breaks the hydrogen bonds causing the chains to unfold
due to the chains now being uncurled they then form intermolecular bonds with other uncurled molecules, changing the shape completely
99
what are some modern uses of essential oils?
```
cosmetics
flavours
dentistry
adhesives
perfumes
medical
cleaning
insect repellents
```
100
what are essential oils?
concentrates, volatile, non-water soluble aroma compounds extracted from plants that contain no artificial substances
100
describe steam distillation
steam passes over the plant and extracts the oil
the mixture evaporates and is passed into a condenser
the essential oil vapour is chilled and collected
100
what is done to terpenes to give the aroma of spices?
they are oxidised
101
how many carbon atoms are in one isoprene unit?
5
102
what are some examples of natural free radical scavengers?
melatonin and vitamin E
103
what is the shortened structural formula for an amide link?
-CONH
105
give an example of a fibrous protein
keratin in hair
106
describe the condensation polymerisation reaction that makes proteins
an amine group of one molecule links to the carboxyl group of another to form an amide link/peptide bond
the hydroxyl group and one hydrogen break off and join to form water which is released
107
what are terpenoids?
oxidised terpenes responsible for the aroma of spices
108
what is ultraviolet radiation?
a high energy form of light present in sunlight
110
what does sun-block do?
prevents UV from reaching the skin
111
what are formed when UV light breaks bonds in molecules?
free radicals
112
what are free radicals?
highly unstable and reactive molecules that have unpaired electrons
113
how are proteins broken down?
by protein hydrolysis during digestion
113
what are the steps in a free radical chain reaction?
initiation
propagation
termination
113
in an initiation reaction where are the free radicals?
the product side of the equation
114
how are esters made?
condensation reaction (or esterification) of an alcohol and a carboxylic acid.
115
what are the 2 types of terpene?
cyclic and linear
