Feature Article
IQBAL ABDUL DHALAIT
Fun With
Chemistry!
E
VERY day we come across many
changes in our surroundings. These
changes may involve one or more
substances. For example, your mother
may ask you to dissolve sugar in water to
make a cold drink. You would also be
familiar with the rusting of iron in which
oxygen molecules from the atmosphere
react with iron atoms in presence of
moisture to form a new substance. The
atoms in iron oxide line up differently from
those in either oxygen molecules or iron.
Again, if we look at photosynthesis,
plants use the energy in sunlight to join
together six molecules of carbon dioxide
and six molecules of water to produce
one molecule of glucose and six
molecules of oxygen. We drink potable
water from the tap or from a bottle. We
may also drink it as lemonade or fruit juice,
tea or coffee. This water has unique
properties because of the way in which
its molecules cling to each other. It is an
oxide of hydrogen, just a chemical but
remarkably unusual. Just add a single
oxygen atom to it and it becomes
hydrogen peroxide with absolutely
different properties.
Isn’t it all so curious? Chemical
reactions happen naturally or can be
made to happen; they may take years or
only an instant. Here are some reactions
laid down before you. Try them at home
and enjoy the fun.
peroxide,
ammonium
hydroxide,
hydrochloric acid, potassium iodide, liquid
detergent, Tincture of Iodine, sodium
thiosulphate, Phenolphthalein pH indicator,
ethyl
alcohol,
water,
potassium
permanganate, glycerin, ammonium
thiocyanate, ferric chloride silver nitrate,
potassium ferrocyanide, ferric chloride,
sodium hydroxide.
1. Change Coca Cola into
Water
Let us suppose you have invited two guests
to your place and one of them is interested
to have Coca Cola while the other wants
plain water. Now, your predicament is that
although you have a bottle of Coca Cola,
you do not have drinking water. Strange
situation, but let’s go along with it.
Now, can you please both of them by
pouring Coca Cola for one from a Coca
Cola bottle and plain water for the other
from the same bottle? Impossible? Well, just
perform this simple chemical trick not for
actually drinking purposes but just to impress
your guests.
Prepare Coca Cola chemically by
mixing sufficient quantities of Tincture of
Iodine in water so as to get dark colour
similar to the Coca Cola drink, store it in a
soft drink bottle and seal it properly well in
advance. Take two empty glasses, put
some crystals of sodium thiosulphate in one
glass well in hand.
Now, open the Coca Cola bottle in
front of your guests and pour some of the
liquid in the empty glass, you will get Coca
Cola. Then pour the remaining liquid from
the same bottle in the other glass
containing crystals of Sodium thiosulphate.
This time you will get plain water. The crystals
of sodium thiosulphate (hypo) react
chemically and decolourise the liquid when
it is poured in the glass. The coloured liquid
dramatically becomes as clear as water!
2. The Crazy Message
Take a blank white paper and write any
message with phenolphthalein indicator
using cotton bud and allow it to dry. Fill the
spray bottle with ammonium hydroxide
solution and spray this solution directly on
the watery marks on the paper. The invisible
message written on the paper will begin to
appear in colour and you will be able to
read it.
But interestingly, after a few minutes
the colour message will start to fade away
and finally completely disappear. Due to
the alkaline nature of ammonium
hydroxide, phenolphthalein gives a pink
colour when it is allowed to mix with the
solution. Further, on exposure to room
temperature the ammonia evaporates
from ammonium hydroxide leaving the
water particle behind on the paper which
is colourless in phenolphthalein indicator.
In this way the message disappears to your
great surprise.
What will you require?
An empty soft drink bottle, drinking glasses,
jug, conical flask or transparent plastic
bottle, rubber cork, rose flower, plate,
paper cup, handkerchief, metal plate/
ceramic plate, knife, cotton bud, blank
white paper, cotton swab, match box,
pairs of tong, glucose powder, methylene
blue indicator, sulfur powder, hydrogen
29
SCIENCE REPORTER, APRIL 2011
Feature Article
First ethyl alcohol starts to burn
since it has a low boiling
temperature as compared to
water.
Water acts like an absorber
3. The Unburnable
Handkerchief
Ask your friend to give
you
his
handkerchief
and get his kind
permission to
burn it. Hardly
likely that you
will get the
permission. Well,
you can perform
this trick with your
handkerchief.
Dip it in a mixture
of ethyl alcohol and water prepared in
the ratio of 1:1. Squeeze out the excess
liquid and hold it with pairs of tong and
then put on the candle flame. You will be
surprised to notice that the handkerchief
catches fire without actually burning.
When you put the handkerchief on
fire, first ethyl alcohol starts to burn since it
has a low boiling temperature as
compared to water. Water acts like an
absorber and absorbs the heat released
by burning the ethyl alcohol helps to keep
the temperature of the cloth down so that
it does not catch fire.
If your friend has been bold and
trusting enough to hand over his
handkerchief, you can now return the
handkerchief without any damage done.
4. Create Fire Magically
Place a metal /ceramic plate on a table.
Put a piece of paper with some potassium
permanganate ground in powder form in
the centre of this plate. Arrange some
pieces of paper on a metal plate. Put two
or three drops of glycerin over potassium
permanganate. The glycerin will slowly start
to react with this black powder by giving
off smoke and very soon the pieces of
paper will start to burn with violet flame.
This is an example of exothermic
reaction in which heat is produced and it
is sufficient to burn the paper pieces.
Unscrupulous people often use this trick to
demonstrate their “supernatural” powers.
But now you know it is just a simple
chemical trick.
Cut Your Hand
Painlessly
Moisten your hand with a
solution of ammonium
thiocyanate and apply ferric
chloride solution with cotton
on the knife blade. Now begin
your demonstration.
5. Cut Your Hand
Painlessly
Can you dare to cut your hand with a
knife? Well, try this simple chemical trick
to impress your friends.
First, before you begin your trick
moisten your hand with a solution of
ammonium thiocyanate and apply ferric
chloride solution with cotton on the knife
blade. Now begin your demonstration.
Hold the knife and press the reverse
edge, the blunt edge, of the knife against
your skin where ammonium thiocyanate
has already been applied. At once a
blood like liquid will flow out of the mark
made by the blade as ammonium
thiocyanate and ferric chloride react. It
will seem as if you have actually cut your
hand and the wound is bleeding.
6. Tri-Colour Change
You must be familiar with the phenomenon
of a turmeric stain on a white shirt turning
red when it is washed with soap. This
happens simply because of the alkaline
nature of the soap solution. This chemical
reaction is another example of colour
change. If you know how to do it, you can
easily turn water into soft drink, milk or even
ink.
Prepare solutions such as ammonium
thiocyanate, silver nitrate and potassium
ferrocyanide by dissolving about a
spoonful of these chemicals into 50 ml
water respectively. Take about 10 drops
of each solution in three glasses and
arrange them side by side on the table.
Prepare another solution of ferric chloride
of the same concentration. Mix it with three
glasses of water in the jug.
Just pour the liquid from the jug into
the first glass and you will get red colour
resembling the soft drink. You will get milk
in the second glass and blue ink in the
third glass. The change of colour to red
and blue are familiar tests for ferric ion
that was already present in the solution.
The white precipitation is a common test
for chlorides. Silver nitrate reacts with ferric
chloride to form a thick white precipitate
of silver chloride resembling milk.
7. Shake It to Get Blue
Colour
Oscillating reactions are truly spectacular
because of the visual display exhibited by
these reactions. Here is one of such
reaction that can be performed with
common chemicals.
Fill three fourth of a conical flask or
transparent plastic bottle with water. Add
about 5 grams sodium hydroxide in it. Add
5 grams of glucose powder and then put
SCIENCE REPORTER, APRIL 2011
30
Feature Article
Now take this flower out of the glass.
Fill the glass halfway with hydrogen
peroxide and dip the rose into it. It will start
to gain its original colour. The sulfur dioxide
which is produced by burning sulfur
combines with oxygen from the coloured
part of the flower leaving the flower
bleached white. The bleached flower is
then dipped in hydrogen peroxide which
provides oxygen to the flower restoring its
colour.
9. Create Smoke without
Burning
a few drops of methylene blue indicator
to this solution and shake them to mix the
dye. The resulting solution will be blue.
Hold and keep the solution steady
and observe any change in colour. The
liquid will gradually become colourless as
glucose reduces the methylene blue dye
and the colour of the solution disappears.
Can you restore this colour again?
To do this just shake the contents of
the conical flask very rapidly by capping
the mouth of the container with cork,
you will be surprised to see blue colour
again. This is due to re-oxidation of
methylene blue with oxygen from the
trapped air. The reaction can be
performed several times by standing
and shaking alternately to make it
happen again and again.
Take a glass, moisten the inside of the glass
with ammonium hydroxide. Take a few
drops of concentrated hydrochloric acid
on the plate. Invert the glass over the plate.
Fumes will start to accumulate in the glass.
8. A Rose of Changing
Colour
The vapors of ammonia combine with
hydrochloric acid to form dense white
fumes of ammonium chloride to give the
effect of smoke.
Take a fresh rose and moisten it with water.
Tape it to the inside of a drinking glass as
shown in the picture. Place a small amount
of sulfur on a metal plate and allow it burn
by providing heat. When it begins to burn,
invert the drinking glass over the burning
sulfur. The flower will start to lose its natural
colour and will become white.
You will be fascinated to see the
tiny bubbles that make the
resulting column of foam that
gushes out look more like
toothpaste.
tiny bubbles that make the resulting
column of foam that gushes out look
more like toothpaste.
11. Boil Water in Paper
Cup
What do you think will happen to a paper
cup of water when it is held over a candle
flame? You would be surprised to know
10. Oxygen Foam
Pour 100 ml of hydrogen peroxide into
a tall glass cylinder. Add some liquid
detergent to it. Mix them thoroughly.
Add about a teaspoonful potassium
iodide in this mixture to make the
hydrogen peroxide break down
chemically. This rapid decomposition
results in lots of oxygen that turns into
foam. You will be fascinated to see the
A Rose of Changing
Colour
Fill the glass halfway with
hydrogen peroxide and dip
the rose into it. It will start to
gain its original colour.
31
that the paper cup will not burn. Let us see
how it is done.
Fill three fourth of a paper cup with
water. Hold the cup a few centimeters
above the candle flame. The paper cup
held over an open flame will not burn
because the heat from the flame transfers
from the cup to the water. Thus the paper
never gets hot enough to burn. Instead,
the transferred heat causes the water to
boil!
Mr Iqbal Abdul Dhalait is an Education Officer with
the Goa Science Centre, Miramar, Panaji-Goa; Ph:
(0832) 2463426
SCIENCE REPORTER, APRIL 2011