Brown's GCSE/IGCSE/O Level KS4 science-CHEMISTRY Revision Notes
Oil, useful products, environmental problems, introduction to
15. Vitamins, drugs-analgesic medicines, food additives and some cooking
What are vitamins?
Drugs-medicines we regularly use! What are food additives used for? How safe are
colourings, flavourings preservatives and sweeteners? What are E numbers? What
is intelligent packaging and active packaging of food? Aspects of cooking
Index of KS4 Science GCSE/IGCSE
Chemistry Oil & Organic Chemistry Pages: 1.
Fossil Fuels : 2. Fractional distillation of crude oil & uses of fractions : 3.
ALKANES - saturated hydrocarbons and combustion : 4.
Pollution, carbon monoxide, nitrogen oxides, what
makes a good fuel?, climate change-global warming :
5. Alkenes - unsaturated hydrocarbons :
6. Cracking - a problem of supply and demand, other products :
7. Polymers, plastics, uses and problems :
8. Introduction to Organic Chemistry - Why so many series of
organic compounds? : 9. Alcohols - Ethanol
- properties, reactions, biofuels :
10. Carboxylic acids and esters : 11. Addition
polymers and condensation polymers :
12. Natural Molecules - carbohydrates - sugars
- starch : 13. Amino acids, proteins,
enzymes & chromatography : 14. Oils, fats,
margarine and soaps :
15. Vitamins, drugs-analgesic medicines & food
additives, cooking chemistry : 16. Ozone, CFC's and free
radicals : 17. Extra notes, ideas and links on
Global Warming and Climate Change : Multiple Choice and Gap-Fill Quizzes:
m/c QUIZ on Oil Products (GCSE/IGCSE easier-foundation-level)
m/c QUIZ on Oil Products (GCSE/IGCSE harder-higher-level) :
IGCSE/GCSE m/c QUIZ on other Aspects of Organic Chemistry
3 Easy linked GCSE/IGCSE Oil Products word-fill worksheets
Vitamins, Drugs-analgesic medicines and Food Additives
What are vitamins?
particular essential molecules with particular roles in living systems
which are NOT proteins, carbohydrates, fats or mineral salts.
If you have a good balanced
diet, you shouldn't, in theory, require any extra dietary supplements.
However, to help avoid potential
vitamin deficiency certain vitamins are added to particular foods such as
bread, margarine, breakfast cereals, milk powder etc. to replace vitamins
destroyed during food processing or to make good a natural deficiency.
One of the most important
ones in any diet is Vitamin C or Ascorbic Acid. Its
structure is related to 'simple' sugars but humans are one of the few
mammals that are unable to synthesise vitamin C.
It is essential for healthy
tissue and one of its functions is the removal of dangerously reactive
chemical species called free radicals (see further on).
Vitamin C is present in
fruit and vegetables but the amount is reduced by prolonged storage and
250 years ago, as many as 2/3
of a ship's crew died from vitamin C deficiency causing scurvy. In 1747 it was
decided to give sailors citrus fruits to recover from scurvy but wasn't until
later that vitamin C was recognised.
In contrast to the other
water-soluble vitamins, vitamin C has no clear cut role as a catalyst or
part of an enzyme. It does, however, have a range of other important
Collagen formation. Vitamin C
in collagen formation which is found wherever tissues
require strengthening, especially in tissues with a protective,
connective, or structural function. Collagen is critical to the
maintenance of bone and blood vessels and is essential in wound healing.
Antioxidant activity. Ascorbic acid can act as an antioxidant by
donating electrons and hydrogen ions, and reacting with reactive oxygen
species or free radicals.
Iron absorption. Vitamin C is important for the effective absorption
of iron and reduces iron(III) Fe3+ to iron(II) Fe2+.
It helps in the
synthesis of vital cell compounds. During times of physical and emotional stress, as well as during
infection, there is increased production of oxygen radicals. Therefore
there is increased reliance on vitamin C's activity as an antioxidant.
Vitamin C is vital for the function of the
immune system, but the effectiveness of large doses of vitamin C in preventing and alleviating
the symptoms of the common cold is still a matter of debate.
Two of the earliest signs
of deficiency (prevention of collagen synthesis) relate to its roles in
maintaining the integrity of blood vessels. The gums around the teeth
bleed more easily, and the capillaries under the skin break
spontaneously producing tiny haemorrhages. If you are short of vitamin C
for say 20 days, scurvy can develop and is characterised
by further haemorrhaging, muscles depletion, rough-brown-dry-scaly skin, deep
bruising. Wounds fail to heal properly and bone fails to rebuild properly
too and you are further likely to suffer from anaemia and infections.
Vitamin A1, A2 and the fat soluble vitamin D
group are found in fish oils.
Vitamin E is found in some vegetable oils
The B group of vitamins
are mainly concerned with metabolism ie the utilization and release of
energy from foods.
EAT yer fruit and veg 'guys' (as well as a few
AND keep yer health and still pass those dreaded exams!!!!
15b Drugs e.g.
in analgesic medicines
Drugs can be defined as
an externally administered substances which modifies or affects chemical
reactions in the body, usually for the bodies greater well-being. Poisons
can be defined in the same way, but hopefully not intentionally and have
undesired effects! A 'drug' is a specific
molecule with a particular pharmacological or physiological action on an
organism/animals chemistry and a medicine is the complete formulation of
the means of administering the drug to a patient i.e. the method of
drugs used to reduce pain and are a type of anti-inflammatory agent.
The molecular structure of
three well known analgesics are shown in the diagram below.
All are used for
'headache' treatment, and hopefully using this website and others
will help minimise their use!
The central hexagonal
ring of 6 carbon atoms is called a 'benzene' or 'aromatic' ring. The 4th
outer electron of carbon (group 4) is delocalised, so the expected 4th
bond per C atom forms part of a 'communal' system (more on this at
advanced level, but the covalence rule of 4 for carbon is not broken!,
you have seen this situation before, check out
You can show a benzene ring as a simple hexagon with a circle in it)
+ NaOH ==>
e.g. An extract of willow
herb extract can be made from the leaves, bark and seeds of the
willow tree. Amongst other ailments it was given to help curing feverish
headaches and relief of pain in childbirth. When ingested the body
hydrolyses and oxidises the naturally occurring 'precursor' molecule to
form salicylic acid* which is the 'active' molecule in the body.
in the 1890's the German chemist Hoffmann experimented with various
chemical modifications of salicylic acid and found the best and
chemically stable form was 'aspirin' (shown below). He tried the
variations on his own father! who survived to provide valuable 'clinical
trials' - hardly acceptable these days! * 'Oil of winter green' from
certain plants is the methyl ester of salicylic acid and has similar
Aspirin (and the others
shown) are not very soluble in water. Soluble
aspirin is made by neutralising the carboxylic acid with the alkali
sodium hydroxide to make the much more soluble sodium salt of the
acid. The reaction, using skeletal formula, is shown in the diagram below the three
analgesic drug structures.
New drugs and testing
Patents are taken out to
protect the company's commercial interests in the new medicine.
There can be a range of
formulations of a particular medicine when you buy it over the counter e.g. tablet of 100% aspirin, soluble aspirin (via Na+ salt of the acid
from neutralisation) and aspirin might form part of a mixture including
substances that have other beneficial effects.
The main point here is that
aspirin, like many drugs, can have multi-functional effects, hopefully
BUT this, sadly, is not
always the case, because with any new drug there is always the
danger of unknown side-effects.
Therefore there is a
tremendous responsibility on pharmaceutical companies to ensure the
development of safe and effective drugs.
Lots of time and money
spent on discovering and developing new drugs and there are lots of
factors to consider:
From the discovery of a
potentially useful molecule, sometimes called the 'lead molecule',
which can be from natural source or produced in some other project
Is there room in the
commercial market place for it?
Do research to see
if its safe, otherwise further development is a waste of time
and money or if not safe, can its molecular structure be
Can the modification
be safe? and more effective?
In what form, can it
be/needs to be, administered in? for clinical trials.
trials in various phases, noting particularly if any side-effects
which may be harmful.
Do you test new
drugs on animals? - an emotive issue, can non-animal testing always
allow the safe development of new products?
Do you test new
drugs on patients in a life threatening situation, give them a last
chance at some risk?
Patient health and
safety issues versus very big drug company commercial interests are
a matter of public concern.
Any new drug must
finally pass all the tests before legally licensed for patient
Additives, Intelligent Packaging and Active Packaging of Food
Food additives are
chemicals added to food to give particular effects e.g.
flavourings preservation and sweetening.
The addition of some of them is controversial i.e. health concerns like
nitrates are carcinogenic, food colourings causing behavioural problems, but
proving these 'cause and effect' claims are not easy.
food more attractive, to fit in with the consumers perception of what it
should look like.
food more 'tasty', less 'bland', and to fit in with the consumers
perception of what it should taste like.
increase the 'shelf-life' of packaged food, decrease risk of food
poisoning by inhibiting bacteria/microbe growth
prevent oxidation of oils/fats by oxygen in the air. Oxygen from air reacts with
food and the
oxidation causes deterioration in quality and taste.
bitterness or pander to our taste!
stabilisers help keep a mixture of ingredients together i.e. prevent
oily/fatty components separate out fro water/aqueous based components.
Processed foods that use
emulsifiers include mayonnaise, biscuits, toffee, bread, extruded
snacks, chewing gum, margarine / low fat spreads, breakfast cereals,
frozen desserts, coffee whiteners, cakes, ice-cream, topping powders,
desserts / mousses, dried potato, peanut butter, soft drinks, chocolate
coatings, caramels etc. etc.
Emulsions provide better
texture, coating ability and appearance, for example in salad dressings, ice
creams, cosmetics and paints.
Aqueous solution chemistry (section on emulsions)
emulsifiers in margarine.
has become more and more important as consumers demand a greater variety of
products which are increasingly sold through super-markets.
A variety of food packing
methods are used, variously described as e.g. intelligent packaging or
active packaging etc.
If the packaging is
air-tight no harmful bacteria can get in.
Excess water can be
removed which inhibits the growth of mould or bacteria.
Air/oxygen can be
removed or replaced with an unreactive gas like nitrogen/carbon dioxide, to
stop oxidation of the food AND removes the need to use antioxidant
E-numbers are reference numbers used by the European Union to
help identification of food additives.
All food additives
allowed and used in the European
Union are identified by an E-number.
The "E" stands for
"Europe" or "European Union".
Normally each food
additive is assigned a unique number, though occasionally, related additives
are given an extension (e.g. a,b,i or ii etc.) to another E-number.
The Commission of the European Union
assigns E-numbers after the additive
is cleared by the Scientific Committee on Food (SCF), the body responsible
for the safety evaluation of food additives in the European Union. A
summary is given below.
- E200-299, preservatives
- E300-399, anti-oxidants,
phosphates, and complexing agents
- E400-499, thickeners, gelling
agents, phosphates, emulsifiers
- E500-599, salts and related
- E600-699, flavourings
- E700-899, not used for food
additives (used for animal feed additives!)
- E900-999, surface coating
agents, gases, sweeteners
- E1000-1399, miscellaneous
- E1400-1499, starch derivatives
- E-numbers are only used for substances added directly to food products, so
contaminants, enzymes and processing aids, which may be classified as
additives in the USA, are not included in the E-number system.
- There is an EU directive on food
labelling which requires food additives
to be listed in the product ingredients whenever they are added for
- This includes colouring, sweetening and
enhancement as well as for preservation, thickening, emulsifying and the
- Ingredients must be listed in descending order of weight, which means
that are generally found close to the end of the list of ingredients.
- However, substances used in the protection of plants and plant products,
flavourings and substances added as nutrients (e.g., minerals, trace elements
or vitamins) do not need to be included in the ingredient list.
this, some substances that are regulated as food additives in other
countries may be exempt from the food additive definition in the EU.
- 15d Some
more aspects of cooking chemistry!
- Is cooking a chemical change?
- Some examples of chemical changes in cooking
Multiple Choice Quizzes and Worksheets
KS4 Science GCSE/IGCSE m/c QUIZ on Oil Products
KS4 Science GCSE/IGCSE m/c QUIZ on Oil Products
KS4 Science GCSE/IGCSE m/c QUIZ on other aspects of Organic Chemistry
3 linked easy Oil Products gap-fill quiz worksheets
ALSO gap-fill ('word-fill') exercises
originally written for ...
... AQA GCSE Science
Useful products from
crude oil AND
... OCR 21st C GCSE Science
Worksheet gap-fill C1.1c Air
pollutants etc ...
... Edexcel 360 GCSE Science
Crude Oil and its Fractional distillation
... each set are interlinked,
so clicking on one of the above leads to a sequence of several quizzes
Level Organic Chemistry revision notes
Revise KS4 Science GCSE/IGCSE/O level
Chemistry Revision-Information Study Notes for revising for AQA GCSE Science, Edexcel
GCSE Science/IGCSE Chemistry & OCR 21stC Science, OCR Gateway Science WJEC/CBAC
GCSE science-chemistry CCEA/CEA GCSE science-chemistry
(and courses equal to US grades 8, 9, 10)
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