The
Science Notebook
Lionel Chem-Lab
- Chapter 6
NOTE: This book was published in 1942 as a manual to
accompany several Lionel Chemistry sets of the time. While
some of the experiments and activities here may be safely
done as written, a number of them use chemicals and methods no
longer considered safe. In addition, much of the
information contained in this book about chemistry and other
subjects is outdated and some of it is inaccurate.
Therefore, this book is probably best appreciated for its
historical value rather than as a source for current information
and good experiments. If you try
anything here, please understand that you do so at your
own risk. See our Terms of Use.
Pages 102 - 111
CHAPTER VI
THE HALOGENS
The halogens, a term meaning "producers of
salt", includes a family of four elements, which, listed according
to their degree of activity, are: fluorine, chlorine,
bromine and iodine. It is natural that
the chemist should group these four elements together because each
possesses certain properties common to the others. When combined
with metals they form compounds strikingly similar to common salt,
hence the name "salt producers".
These elements are of the utmost commercial
importance. Chlorine undoubtedly is the most essential of the four
due to its industrial use in munitions, bleaching and
disinfecting. Sodium chloride and hydrochloric acid are two very
important compounds of chlorine which have many wide uses not only
in medicine but in the chemical industries.
The other three elements and their compounds
enjoy a multitude of applications in the field of drugs, dyes,
medicines, antiseptics, bleaching agents and photographic
chemicals.
FLUORINE
Fluorine is one element which few people have
ever seen because of its rarity and the great difficulty required
to prepare it. Since it is very active, its compounds occur
abundantly in the earth as calcium fluoride (fluorspar) and
cryolite. In its free state, poisonous fluorine is a pale yellow
gas somewhat heavier than air with a pungent odor.
Hydrogen
fluoride, one of the important compounds of fluorine, is
a liquid prepared by the action of sulfuric acid on fluorspar.
When this liquid is dissolved in water, hydrofluoric acid is formed. One of the
peculiarities of this acid is that it is very corrosive and
attacks glass. For this reason, chemists have to keep it in wax
bottles, and handle it with the utmost caution. However, the fact
that it does attack glass makes it most useful in etching and
frosting processes. Frosted light bulbs, for example, are etched
on the inside by the action of hydrofluoric acid.
EXPERIMENT No. 131 A Test For Calcium Fluoride
(CL-66, CL-77)
APPARATUS:
Calcium fluoride, heating spoon and alcohol lamp.
102
LIONEL
CHEM-LAB 103
PROCEDURE:
Place one measure of calcium fluoride in the heating spoon and heat
it, using a blowpipe if necessary. Continue heating until the
substance fuses or melts. Moisten a piece of litmus paper and place
it on the melted substance.
SUMMARY:
When calcium fluoride is heated, it either melts or fuses and causes
red litmus paper to turn blue.
EXPERIMENT No. 182 Testing For Florine
(CL-66, CL-77)
APPARATUS:
Calcium fluoride, glass tubing, sodium bisulfate and alcohol lamp.
PROCEDURE:
Mix one measure of calcium fluoride and one measure of sodium
bisulfate on a clean sheet of paper. Place one end of a section of
glass tubing in the flame of the alcohol lamp. Rotate the tubing
between your fingers and heat until the end closes. Allow the tubing
to cool. Put some of the mixture into the tube and follow the same
procedure to close the other end of the tube. Heat the mixture and
note the white smoke formed inside the closed tube.
CAUTION:
Care should be taken not to smell too much of this gas since it
attacks the membranes of the nose, throat and lungs.
SUMMARY:
Sulfuric acid formed by heating the sodium bisulfate, reacts with
calcium Huoride to form hydrofluoric acid. The fumes will etch
glass.
EXPERIMENT No. 183 Decomposition Of Calcium
Floride
(CL-66, CL-77)
APPARATUS:
Calcium fluoride, glass tubing, sodium bisulfate, alcohol lamp.
PROCEDURE:
Repeat Experiment No. 182 and pay particular attention to the white
residue which forms on the walls of the glass tube.
SUMMARY:
Sulfuric acid reacts with calcium fluoride to form hydrofluoric acid
(the smoke) and a silicate (the residue).
CHLORINE
Scheele, a Swedish druggist, is generally
credited with having discovered the important element of chlorine, a gas so-named
because of its greenish-yellow color. It does not occur free in
nature but in combination with numerous minerals. Although
existing in many harmless compounds, free chlorine is very dangerous. During the
First World War, it was commonly used as poison gas and for this
reason, in performing the following experiments, we must be very
careful not to smell too closely any of the fumes from the test
tube even though only slight traces of the gas will be prepared.
Chlorine compounds are all about us, the one
familiar to every boy and
104 THE
HALOGENS
perhaps the most indispensable of all is sodium
chloride, or common table salt. Other important chlorides (where
chlorine is combined with a metal) are potassium chloride and
magnesium chloride.
HOW CHLORINE IS MANUFACTURED
Inasmuch as no free chlorine is found in
nature, it has to be obtained from its compounds. Commercially,
this is done by the electrolysis of salt water. Electricity
conducted through salt water results in the formation of chlorine
gas. This same reaction, as you may know, has caused the death by
chlorine asphyxiation of scores of men on wrecked submarines when
salt water has reached the electric batteries used to propel the
submarine under water.
The electrolytic method is as follows: Solid
sodium or potassium chloride is first dissolved in water to make a
brine. This is purified and then subjected to the influence of
direct electric current in electrolytic cells. The products thus
obtained are chlorine gas, sodium or potassium hydroxide solution,
and hydrogen gas. The chlorine gas is purified, compressed, and
cooled to a yellow liquid which is loaded into clean containers
ready for shipment.
One of the largest chlorine plants is located
at Niagara Falls where an abundance of electric power makes the
electrolytic method of producing chlorine economical. Sodium
hydroxide and hydrogen are valuable byproducts. In the laboratory,
chlorine is usually prepared by oxidizing hydrochloric acid with
manganese dioxide.
EXPERIMENT No. 184 Preparation Of Chlorine
(CL-66, CL-77)
APPARATUS:
Manganese dioxide, hydrochloric acid, filter paper, starch test
solution, two test tubes, delivery tube and stopper, candle or
alcohol lamp.
PROCEDURE:
Place one measure of manganese dioxide and ten drops of hydrochloric
acid in a test tube. Insert the delivery tube and stopper into the
mouth of the test tube. Heat the solution to the boiling point,
remove from flame and collect the gas in the other test tube.
Prepare some starch test solution as described in Experiment No.
688. Pour a little of this solution on a piece of filter paper. Hold
a piece of this test paper over the mouth of the tube containing the
gas and note the resulting color.
SUMMARY:
Manganese dioxide reacts with hydrochloric acid to form manganese
chloride, water and chlorine gas, When starch test paper is exposed
to this gas it acquires a bluish color.
CAUTION:
The residue in the first test tube should be destroyed or the
chlorine gas will continue to be generated. Care should be taken
LIONEL CHEM-LAB 105
not to smell too much of the gas since it
attacks the membranes of the nose, throat and lungs.
EXPERIMENT No. 185 How To Prepare Chlorine
(CL-55, CL-66, CL-77)
APPARATUS:
Calcium hypochlorite, tartaric acid and test tube.
PROCEDURE:
Put two measures of calcium hypochlorite in a test tube half full of
water and shake to dissolve. Add one measure of tartaric acid and
observe the resulting gas bubbles. Carefully note the odor coming
from the mouth of the tube.
CAUTION:
Care should he taken not to smell too much of this gas since it
irritates the membranes of the nose, throat and lungs.
SUMMARY:
In this reaction, the chlorine of the calcium hypochlorite is
liberated as a gas. It is easily detectable because of its
penetrating odor.
EXPERIMENT No. 186 Detecting Chlorine
(CL-55, CL-66, CL-77)
APPARATUS:
Starch, sodium iodide solution, white paper, calcium hypochlorite,
tartaric acid, two test tubes, alcohol lamp or candle.
PROCEDURE:
Place in a test tube one measure of starch, a few drops of water,
and three drops of sodium iodide solution. Add one half a test tube
of boiling hot water. Heat this solution until it boils. Allow to
cool. Put two measures of calcium hypochlorite in a second test tube
half full of water and shake vigorously. Add two measures of
tartaric acid to the calcium hypochlorite solution. Heat gently and
note the odor of chlorine gas. Dip the white paper into the starch
solution and place the wet paper over the mouth of the test tube
containing the gas.
SUMMARY:
When the chlorine gas comes in contact with the starch test paper,
it reacts with the sodium iodide to form sodium chloride and
liberates free iodine which turns blue in the presence of starch.
EXPERIMENT No. 187 Protection Against Chlorine
{CL-55, CL-66, CL-77)
APPARATUS:
Sodium thiosulfate, sodium carbonate, cotton, calcium hypochlorite,
tartaric acid and two test tubes.
PROCEDURE:
Pour three measures of sodium thiosulfate and three measures of
sodium carbonate in a test tube half full of water. Shake to
dissolve. Soak a wad of cotton in this solution for two or three
minutes. Allow to dry. Dissolve one measure of calcium hypochlorite
in another test tube half full of water. Close the mouth of the test
tube with your thumb and shake vigorously. Add one measure of
tartaric acid. Place the wad of cotton over the mouth of the second
test tube which is generating chlorine gas. Smell cotton and note
the absence of any odor.
106 A THE HALOGENS
SUMMARY:
The sodium thiosulfate converts the chlorine into a harmless
substance and renders it odorless.
EXPERIMENT No. 188 Testing For Chlorine In
Organic Compounds
(CL-66, CL-77)
APPARATUS:
Thin copper wire, carbon tetrachloride, alcohol lamp.
PROCEDURE:
Bend one end of the copper wire into a loop about one eighth of an
inch in diameter. Hold loop over flame until the flame loses its
bright color. Allow to cool. Dip wire into carbon tetrachloride
bottle and reheat it immediately. Note the green colored flame.
SUMMARY:
Organic compounds containing chlorine give a green color to the
flame.
EXPERIMENT No. 189 How Chlorine Reacts To Copper
(CL-55, CL-66, CL-77)
APPARATUS:
Calcium hypochlorite, tartaric acid, piece of copper, test tube,
delivery tube and stopper, candle or alcohol lamp.
PROCEDURE:
Place two measures of calcium hypochlorite in a test tube filled
with water. Shake vigorously. Add two measures of tartaric acid.
Attach delivery tube and stopper. Heat gently. Place a piece of
copper in the stem of the delivery tube. Note the tarnishing of the
metal.
SUMMARY:
The tarnishing of the copper is due to the chlorine. Chlorine is
very active and all the familiar metals, with the possible exception
of gold and platinum, react readily with it.
EXPERIMENT No. 190 Chlorine And Sodium
Thiosulfate
(CL-55, CL-66, CL-77)
APPARATUS:
Sodium thiosulfate, calcium hypochlorite, tartaric acid, gas
delivery tube and stopper, two test tubes.
PROCEDURE:
Place three measures of sodium thiosulfate in a test tube half full
of water and shake to dissolve. Dissolve two measures of calcium
hypochlorite in another test tube half full of water. Add two
measures of tartaric acid to the calcium hypochlorite solution.
Quickly attach gas delivery tube and stopper to the tube of calcium
hypochlorite solution with the long stem running into the sodium
thiosulfate test tube. Note the white precipitate when the chlorine
gas passes into the test tube of sodium thiosulfate.
SUMMARY:
This reaction causes sodium thiosulfate to decompose and form
sulfur, which settles as a white precipitate. The chlorine reacts
with the sodium to form sodium chloride. Thus, the chlorine is
converted into a harmless substance by the sodium thiosulfate.
Of the many uses of chlorine, the two
principal ones are in bleaching and purification of drinking
water.
LIONEL
CHEM-LAB 107
Chlorine forms bleach liquor when absorbed in water or in lime
or alkali solutions, and such solutions are widely used as
bleaching agents in the textile, pulp and paper, shellac and other
manufacturing industries as well as in households and laundries.
Calcium hypochlorite is an example of a chlorine compound used for
bleaching.
The pulp and paper industry is the largest
industrial consumer of chlorine, while the second most important
application is in the manufacture of organic chemicals.
EXPERIMENT No. 191 How Chlorine Bleaches Cloth
And Paper
(CL-55, CL-66, CL-77)
APPARATUS:
Calcium hypochlorite, bits of colored paper, some small pieces of
dyed cotton cloth, acetic acid, saucer and glass.
PROCEDURE:
Place five measures of calcium hypochlorite in a glass containing
about an inch of water. Stir solution thoroughly. Drop in the paper
and cloth. Add three drops of acetic acid and cover glass with a
saucer. Set the glass aside for a few hours. Take out the materials,
rinse with water and allow to dry. Note how the colors have been
bleached.
SUMMARY:
Calcium hypochlorite, or bleaching powder, as it is commonly called,
is an unstable compound giving off chlorine in the presence of an
acid. This chlorine gas sets the oxygen free from the water and the
oxygen so liberated combines with the dye substance in the cloth or
paper converting it into a colorless compound. Care should be taken
not to expose the materials to chlorine for too long a time or the
gas will injure the fabrics.
The use of chlorine for the sterilization of
water and sewage is increasing markedly, an application of utmost
importance to National Health. Practically every city must purify
its water supply and chlorine is used for this purpose. The
terrible disease of typhoid has been practically eliminated from
our American cities because our drinking water is now chlorinated.
Useful chlorine compounds are chloroform and carbon tetrachloride.
EXPERIMENT No. 192 Carbon Tetrachloride
(CL-66, CL-77)
APPARATUS:
Carbon tetrachloride, test tube, heating spoon and candle.
PROCEDURE:
Place one drop of carbon tetrachloride in a test tube half full of
water. Note where the drop settles. Shake the tube well. Note
whether the carbon tetrachloride dissolves. Place a drop on your
hand and blow on it. Note the cooling effect. Place several drops in
the heating spoon and attempt to ignite the liquid. Note that the
liquid does not burn.
SUMMARY:
Carbon tetrachloride is one of the many organic compounds containing
chlorine. It is heavier than water and will not
108 THE
HALOGENS
mix with it. The cooling effect is due to rapid evaporation. Because
it is non-inflammable and can remove grease spots from fabrics,
carbon tetrachloride is used extensively as a cleaning agent in the
home. (Gasoline is considered very dangerous as a spot-remover and
should never be used.)
HYDROCHLORIC ACID
Chlorine has a special affinity for hydrogen.
The two gases may be mixed in the dark without danger but an
electric spark or bright sunlight will cause an immediate
explosion since the two combine violently to form hydrogen chloride, a very
important compound which forms hydrochloric acid when dissolved in
water.
Commercially, hydrochloric acid is manufactured
by heating sodium chloride and sulfuric acid and dissolving the
resulting gas in water.
EXPERIMENT No. 193 How To Prepare Hydrochloric
Acid
(CL-11, CL-22, CL-33, CL-44, CL-55, CL-66, CL-77)
APPARATUS:
Sodium bisulfate, ammonium chloride (or sodium chloride), test tube,
glass rod, household ammonia, candle or alcohol lamp, and blue
litmus paper.
PROCEDURE:
Put three measures of sodium bisulfate into a dry test tube. Add two
measures of ammonium chloride or sodium chloride. Heat cautiously
over a flame keeping your face away from the reaction. Note the
rising of fumes. Place a strip of moistened blue litmus paper over
the mouth of the test tube and note the reaction. Remove tube from
flame and cautiously inhale the odor at mouth of tube. Insert glass
rod into some household ammonia. Hold the rod near the mouth of the
test tube. Note the appearance of white fumes.
SUMMARY:
When heat was applied, hydrogen chloride gas was liberated changing
the dampened blue litmus paper red. This gas is readily soluble in
water and in such a solution is called hydrochloric acid.
EXPERIMENT No. 194 Properties Of Hydrochloric
Acid
(CL-44, CL-55, CL-66, CL-77)
APPARATUS:
Blue litmus paper, hydrochloric acid, test tube, candle or alcohol
lamp.
PROCEDURE:
Place a drop of hydrochloric acid on a strip of blue litmus paper.
Note that the litmus paper turns red. Place two drops of
hydrochloric acid in a test tube. Hold the test tube in the upper
portion of flame and heat. Remove test tube from flame. Note the
sharp odor. Place moistened strip of blue litmus paper at mouth of
tube. Note the red color change.
SUMMARY:
The changing of blue litmus paper to red is proof that the liquid is
an acid. When heated, the hydrogen chloride fumes
LIONEL
CHEM-LAB 109
escape (detectable because of their sharp odor). This too is acid in
reaction as it changes moistened blue litmus paper red.
SODIUM CHLORIDE OR SALT
Probably no other substance except water is
more used by civilized people than salt. It occurs in nature in
three different forms, first in sea water, second in salt springs
and third as rock salt.
The oldest method of making salt is to
evaporate salt water, and this method, although crude, is still
used today in many parts of the world.
The customary method of obtaining salt is by
means of wells drilled into the deposits. Two pipes, one inside
the other, are used and water forced down between the pipes brings
salt brine to the surface via the inside pipe.
BROMINE
Bromine is a thick, light-colored liquid with
an extremely disagreeable odor. It is similar to chlorine and
fluorine in that it is very poisonous in both its liquid and
gaseous state. Small amounts of bromine are found in salt water
and can be obtained by evaporating the water. Bromine compounds
are known as bromides.
The principal uses of bromine are in medicine and photography, but
in recent years it has achieved considerable popular recognition
because of its use in tear gas.
IODINE
Iodine, the fourth and last member of the
Halogen family, is by no means the least important. Originally
discovered over a hundred years ago by a French chemist, to the
average boy it is probably best known because of tincture of iodine, the
dark-brown antiseptic which smarts when applied to a cut or wound.
EXPERIMENT No. 195 How To Prepare Iodine
(CL-55, CL-66, CL-77)
APPARATUS:
Sodium iodide solution, sodium bisulfate, calcium hypochlorite and
test tube.
PROCEDURE:
Place two drops of sodium iodide solution in a test tube half filled
with water. Add a quarter-measure of calcium hypochlorite and a
measure of sodium bisulfate. Shake tube vigorously for a few
seconds. Note the brownish-yellow color.
SUMMARY:
When calcium hypochlorite is mixed with water in the presence of an
acid, chlorine is liberated. This gas, being more active than
iodine, displaces it readily from the sodium iodide solution. The
free iodine turns the solution brownish-yellow.
110 THE
HALOGENS
EXPERIMENT No. 196 Starch Test Detects Iodine
(CL-55, CL-66, CL-77)
APPARATUS:
Three test tubes, white paper, starch, sodium iodide solution,
sodium bisulfate, calcium hypochlorite, eye dropper, candle or
alcohol lamp.
PROCEDURE:
Add half a test tube of water to a test tube containing one measure
of starch and a few drops of water. Boil for a few seconds and
immerse the piece of white paper in the solution. Take paper out and
dry. Place two drops of sodium iodide solution in a test tube half
full of water. Add one measure of sodium bisulfate and a pinch of
bleaching powder. Shake well and then place the dried starch paper
into this iodine solution.
SUMMARY:
A starch test solution under proper conditions will show a very
definite blue color in the presence of iodine.
EXPERIMENT No. 197 Iodine Soluble In Carbon
Tetrachloride
(CL-66, CL-77)
APPARATUS:
Carbon tetrachloride, sodium iodide solution, sodium bisulfate,
calcium hypochlorite and test tube.
PROCEDURE:
Prepare iodine by placing one drop of sodium iodide solution in a
test tube half full of water. Add a quarter measure of calcium
hypochlorite and one measure of sodium bisulfate. Shake tube a few
seconds. Add several drops of carbon tetrachloride. Shake tube
vigorously. Hold tube still and allow carbon tetrachloride to mass
at the bottom. Note the violet color.
SUMMARY:
Iodine is more soluble in carbon tetrachloride than in water. Carbon
tetrachloride being heavier than water settles at the bottom of the
tube, carrying with it most of the iodine. This accounts for the
violet color at the bottom of the test tube.
EXPERIMENT No. 198 Iodine Reacts With Sodium
Thiosulfate
(CL-55, CL-66, CL-77)
APPARATUS:
Sodium thiosulfate, sodium iodide solution, sodium bisulfate,
calcium hypochlorite and two test tubes.
PROCEDURE:
Pour two drops of the sodium iodide solution into a test tube half
full of water. Add one measure of sodium bisulfate and a pinch of
calcium hypochlorite and shake well. Note the reddish brown color.
Now put two measures of sodium thiosulfate into this iodine solution
and note that the color disappears.
SUMMARY:
Sodium thiosulfate reacts with iodine converting it into two
colorless compounds.
EXPERIMENT No. 199 Iodine Stain Remover
(CL-33, CL-44, CL-55, CL-66, CL-77)
APPARATUS:
Sodium thiosulfate, test tube and iodine stain.
LIONEL
CHEM-LAB 111
PROCEDURE:
Dissolve five measures of sodium thiosulfate in a test tube half
full of water. Apply to the iodine stain and note that the stain
disappears in a short time.
SUMMARY:
This is added proof that sodium thiosulfate converts iodine into
colorless compounds.
EXPERIMENT No. 200 Iodized Salt Contains Iodine
(CL-55, CL-66, CL-77)
APPARATUS:
Sodium bisulfate, glass, stirring rod, iodized salt, test tube,
starch and calcium hypochlorite.
PROCEDURE:
Dissolve by stirring, three measures of sodium bisulfate and two
teaspoonfuls of iodized salt in a glass half full of water. Add one
measure of calcium hypochlorite and stir. Prepare some starch
solution by adding a test tube half full of boiling water to a test
tube containing one measure of starch and a few drops of water. Boil
for a few seconds. Pour a few drops of the cooled starch solution
into the above solution and note the blue color. The blue color is
proof that the salt contains iodine.
"The Science Notebook"
Copyright 2008-2018 - Norman Young