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Chemistry: a useful subject! By Marietta Begley/Loreto College, Coleraine.
Chemistry:
a useful subject!
By
Marietta
Begley/Loreto
College,
Coleraine.
Do we really
believe that chemistry is of benefit to us? Of course we do here is some of the
uses of elements and compounds. It
is aimed at GCSE standard but may be useful to other levels as well.
1)
Ever got your zip caught on your way out the front door ?.
Simply rub
a pencil lead up and down it
a few times and it should work perfectly!
This is due to
the composition of graphite an allotrope of Carbon. You might just
think that carbon is something you find in coal but it is part of a great many
things. The fact that the molecules
in Carbon are joined together by weak ‘Vann der Waals’ forces helps explain
why it works that way.
There exists weak Vann der Waals forces
between the layers of covalently bonded carbon.
These layers are almost like sheets of chicken wire in shape.
Between each rigid layer
there is weak forces , which can break and form again easily.
This quality helps when it
is being used as a lubricant because the sliding past one another of the layers
means that the system can move smoothly along.
2)
During the Christmas holidays
your lovely old aunt always sends you some of her home-made shortbread.
The trouble is by the time you get them by air mail they’re very soggy.
Problem solved!. Next time
you buy an item of electrical goods keep the little sachet of silica gel that
comes in the box. The silica gel is
a deliquescent substance which
means it can be used as a drying
agent. Another chemical which acts
as a drying agent is Calcium Chloride which is a hygroscopic substance. These
could mean that when you get your auntie’s biscuits they are in perfect
condition.
3)
Having trouble getting peppers
to ripen in the garden simply place a banana skin alongside.
The esters present in the banana help to induce the ripening of the
fruit. Another gardening tip is for hydrangeas.
You can change the colour of your plant by simply placing a few rusty
nails in the soil below. In acid ground the plant flourishes ‘pinky-red’ blooms and
in more alkali soils ‘blue’ blooms form.
4)The pain of a Bee sting can be easily cured by crushing up an aspirin
and rubbing it into the sore. The
aspirin is an ant-acid substance and neutralises the acid bee sting.
Likewise if you have no aspirin then try rubbing a little bicarbonate of
soda into the sting. It is alkaline
and so as a basic substance
neutralises the acid injected by the sting.
Here is an A-Z
guide of some chemicals and their uses.
ALUMINIUM: in
alloys, cooking foil, cans, saucepans, stepladders, window frames,
aircrafts, overhead power cables, milk
bottle tops and mirrors.
ALUMINIUM
HYDROXIDE : ant-acid(medicine)
AMMONIA:
fertilisers(both nitrogen only and nitrogen combined), in the production of
Nitric acid, in turn making explosives and nylon.
ARGON:
incandescent light bulbs, in welding and so-called neon signs.
CALCIUM: used in
bones and teeth.
CALCIUM CARBONATE:
heated to form CALCIUM OXIDE ,’Quicklime’ used in cement production.
‘Quicklime is also converted to lime (calcium hydroxide) and added to soils to
make them less acid.
CALCIUM CHLORIDE:
hygroscopic drying agent.
CALCIUM HYDROXIDE:
for lime to neutralise soils.
CALCIUM SULPHATE:
chalk production, paint in road markings, plaster and plasterboard, heated with
coke to produce ‘Quicklime’ and in ‘Plaster of Paris’.
CARBON: charcoal,
cutting tools, jewels, pencil ‘leads’.
CARBON DIOXIDE:
fire extinguishers, ‘dry ice’ , and ‘fizzy’ drinks.
CHLORINE:
bleaching cotton, linen and wood pulp; in the production of PVC, making solvents
with hydrocarbons and making of hydrochloric acid.
COPPER: electrical cables and fittings( ductile) ; alloyed to make Brass
and bronze; used in pipes for plumbing.
ETHANOIC ACID: a very dilute solution is used as vinegar
ESTERS: some make good solvents, sometimes they are present naturally in
foods giving a fruity smell.
ETHANOL: used in alcoholic beverage production, as a solvent in
cosmetics and a fuel in some
countries.
HELIUM: used to fill airships (low density and inert), used in so called
neon signs(cream).
HYDROCARBONS: used in natural gas; present in coal, lignite, petrol, diesel, paraffin oil, grease and
candle wax; as well as being used in the production of useful plastic polymers.
HYDROGEN: in rocket fuel (along with liquid oxygen); for filling
meteorological balloons; making margarine and as a clean fuel, producing water
and energy only.
IRON: present in the Haemoglobin of the body, enabling it to carry
oxygen; also in the blast furnace in the production of steel.
LEAD: used in roof “flashing” to seal the gap between roof and
chimney; to shield when radioactive sources are used; in car batteries to make
the electrodes.
MAGNESIUM: usually made into corrosion resistant alloys which are used
in bicycle and aircraft frames.
NITROGEN: in its liquid form used to freeze convenience foods(bacteria
have less time to multiply); used in the packaging of foods to remove moisture.
OXYGEN : in hospital breathing apparatus; in welding and in rocket fuel.
SILICA GEL: used as a desiccant (absorbing moisture from the air) in
goods such as electrical equipment, biscuits
shoes e.t.c
SILICON: second most abundant element on earth: it is a semi-conductor
and is used in microchips.
SILICATES: used in building material; cements; pigments and detergents.
SILVER BROMIDE: used to make photographic film.
SODIUM HYDROGEN CARBONATE: used as a raising agent in baking; dissolves
readily in water to form an ant-acid to neutralise the stomach.
SODIUM HYPOCHLORITE: used in bleaches to kill germs and whiten clothes.
SODIUM HYDROXIDE: strong alkali used in soap production.
SODIUM SALTS: used in glass production; added to sand and grit in the
form of rocksalt to spread on the roads in winter to prevent them from being
unsafe.
SULPHUR: in the vulcanisation process(rubber heated with sulphur does
not become hot and sticky as it gets warmer);also used to kill pesticides.
SULPHUR DIOXIDE: used in the bleaching of wood pulp ;caution needed as
it is a toxic substance to most life forms and is used in certain cases as a
preservative atmosphere around some foods and is also used as a fumigant.
SULPHURIC ACID: used in
industry to produce fertilisers, fibres, detergents, paints and is also used in
the production of car batteries in which it is the electrolyte.
WATER: everyday uses include cooking, cleaning, washing e.t.c but it is
mainly used as a coolant in many Industrial processes.
ZINC: used in the galvanisation of Iron (sacrificial protection); in the
making of the alloy Brass for light fittings and door knobs; also used in
batteries as electrodes (mainly dry cell).
These are the main substances that are mentioned at GCSE level in the
syllabus.
However it is hoped that the information
here and the links to other sites will be of great benefit to someone.
This site is currently under construction ; hold on to your seats in
anticipation of new information!
Thanks to Marietta
Begley: Chemistry Department: Loreto College, Coleraine.
