1 Chlorine, a greenish yellow gas is rarely found in
pure form, but as compounds in rock salt. It is commonly found in seawater. Carl
Wilhelm Scheele first discovered this element in 1774 after extracting it from
the mineral pyrolusite, but it was Sir Humphry Davy who named it in 1810.
Water Chlorination
2 The World Health Organization reported that adding
chlorine to water has helped to increase life expectancy in the USA from a mere
45 to roughly 77 years. Water chlorination kills dangerous pathogens including
typhoid, cholera and dysentery by oxidization, making water safe to drink.
3 Chlorine’s chief use is as a disinfectant and is
added routinely to drinking water and swimming pools. Paper factories, paint,
textiles, insecticides, medicines and antiseptics also use chlorine for cleaning
and as a solvent.
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| Chlorine Tablets for Swimming Pools |
4 Chlorine Properties
Atomic number: 17
Atomic weight: 35.453
State: Greenish yellow gas
Category: halogen
Melting point: -102°C (-151°F)
Boiling point:
-34°C (-29°F)
5 The disinfectant smell of swimming pools is
attributed to chlorine. Conversely, a strong chlorine smell is a sign of a
dirty pool, as by-products of chlorine emit odours as bacteria are killed. Nowadays,
pools are shock-chlorinated with large amounts of sodium hypochlorite to mass-kill
bacteria. Only once the chlorine levels are low, is the (now clean) pool safe
to swim in.
6 Despite the health benefits of chlorinating water,
by-products of over-chlorination can cause side effects such as fatigue and in
high doses, cancer of the kidneys and liver as well as heart disease. For this
reason, levels of chlorine in water supplies are constantly monitored to ensure
they are low.
Chlorine Gas
7 Chlorine’s antiseptic qualities are in fact because it
is toxic. In liquid form will irritate mucous membranes and burn the skin. In
gas, can be lethal after a mere few breaths in concentrations of 1000 parts per
million. In 1915, the Germans released
chlorine gas over the trenches of the British, killing thousands of soldiers.
Potassium Chloride Uses
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| Chlorine Symbol |
8 Chlorine is present in table salt, hence sodium
chloride but its uses are not confined to seasoning food. The chloride in salt
provides a safe antiseptic for cleaning contact lenses and surgical equipment.
Salts are also fed via intravenous drip to balance the body’s electrolytes.
Potassium chloride is a pharmaceutical mineral salt used to treat potassium
deficiency.
Hydrogen Chloride
9 Chlorine is also present in our stomachs in the form
of hydrochloric acid (chlorine bonded with hydrogen), without which proteins
could not be broken down for digestion. Hydrochloric acid is one of the most
corrosive substances known to man, which also makes it invaluable for industrial
processes, such as cleaning, refining metals and in fertilizer production.
What is Chloroform?
10 Chloroform, (a chloromethane), a thick, colourless
liquid, is one of the first anaesthetics to be used after obstetrician James
Young Simpson discovered for himself how inhaling the vapours spurred
unconsciousness. But using it as pain relief for childbirth caused controversy
with the church, as it was seen to be interfering with God’s way. This didn’t
stop Queen Victoria from using chloroform when bearing two of her children.
11 It is chlorine that bleaches paper white. In fact,
when added to clothes, or anything, it will make it whiter. This is because
chlorine is a key ingredient in bleach.
12 Chloride is used in plastic known as PVC, or poly-vinyl-chloride.
Being weatherproof, tough and heat resistant, is a favoured material for pipes,
windows, doors and guttering on millions of homes.
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