The
Science Notebook
Lionel Chem-Lab
- Chapter 13
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subjects is outdated and some of it is inaccurate.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 159 - 162
CHAPTER XIII
THE ALKALI METALS: SODIUM AND POTASSIUM
Sodium and potassium are commonly called the alkali metals because their
hydroxides are strong bases or alkalis. Although there are five
metals in this group, only sodium and potassium are of commercial
importance and we shall quickly pass over the other three.
Ordinarily we think of metals
as being hard substances and comparatively inactive, but sodium
and potassium refute this common impression. They are soft enough
to be cut with a knife, light enough to float on water, and they
melt at a lower temperature than that at which water boils. Both
sodium and potassium combine so readily with water and oxygen in
the air, and so much heat is evolved, that the chemist has to keep
them immersed in kerosene.
Because they are so active, sodium and
potassium do not occur in the native state, but combined with
other elements they exist in dozens of common, well-known
compounds. Sodium chloride
(common table salt), sodium
nitrate, and sodium
tetraborate (borax) are examples of some of the more
important sodium compounds. Among the potassium compounds, potassium chloride, potassium nitrate, potassium carbonate (potash)
and feldspar are the
principal ones.
SODIUM COMPOUNDS
The chemical name for ordinary table salt is sodium chloride, and although
we are inclined to think of it only as a seasoning for our food,
the fact remains that it has many other important uses. Because it
is so easily obtainable, salt is used in the preparation of
practically all the sodium and chlorine compounds, including soda,
glass, soap, chlorine, hydrochloric acid and bleaching powder.
Sodium
hydroxide, an important base manufactured in large
quantities, is used in many products including soap, petroleum,
dyes and rayon. Lye and
caustic soda are other
names for sodium hydroxide.
EXPERIMENT No. 344 Preparation Of Sodium
Hydroxide
(CL-11, CL-22, CL-33, CL-44, CL-55, CL-66, CL-77)
APPARATUS:
Sodium carbonate, calcium oxide, three test tubes.
PROCEDURE:
Dissolve three measures of sodium carbonate in a
159
160 THE
ALKALI METALS
test tube half full of water. Dissolve two measures of calcium oxide
in another test tube containing the same amount of water. Mix the
two solutions thoroughly. Filter into a clean test tube. The
filtrate is sodium hydroxide.
EXPERIMENT No. 345 A Test For Sodium Hydroxide
(GL-11, CL-22, CL-33, CL-44, CL-55, CL-66, CL-77)
APPARATUS:
Calcium oxide, sodium carbonate, test tubes, red litmus paper.
PROCEDURE:
Prepare a solution of sodium hydroxide as described in the preceding
experiment. Drop a piece of moistened red litmus paper into the test
tube. Sodium hydroxide being a base will change
red litmus paper blue.
Sodium hydroxide dissolves animal fibers of
wool and silk, but has little, if any, effect on cotton and linen
which are vegetable fibers. Because of this, it is a test used to
determine whether or not a fabric is made from wool or cotton.
Sodium
carbonate (washing soda) and sodium bicarbonate (baking soda) are important
sodium compounds. They are both produced by the Solvay Process, in which the
bicarbonate is formed simultaneously with the carbonate.
The principal uses of sodium carbonate are in the making of soap
products and glass. Sodium bicarbonate, or ordinary white baking
soda, can be prepared by bubbling carbon dioxide into a saturated
solution of sodium carbonate.
EXPERIMENT No. 346 Preparation Of Sodium
Bicarbonate
(CL-77)
APPARATUS:
Erlenmeyer flask, test tubes, sodium chloride, household ammonia,
alcohol, filter paper, funnel, gas generator, delivery tube and
beaker.
PROCEDURE:
Place one test tube full of water and two tablespoons of sodium
chloride in the Erlenmeyer flask. Stopper the flask and shake
thoroughly for two or three minutes. Allow the excess salt to
settle. Then decant one quarter test tube of solution into a dry
test tube and add one half test tube of household ammonia and mix
thoroughly. Add one quarter test tube of alcohol and mix again.
Prepare carbon dioxide gas as described in Experiment No. 151.
Attach delivery tube of the gas generator so that the end of the
tube reaches well below the surface of the solution in the test
tube. Allow the carbon dioxide gas to bubble through the solution
while shaking the test tube. Continue adding carbon dioxide until no
more bubbles appear. Within ten to fifteen minutes, a precipitate
will form. Filter and add one quarter test tube of alcohol to the
precipitate. Wash the precipitate with water. Remove precipitate
from filter paper and spread it on a clean paper towel to dry.
LIONEL
CHEM-LAB 161
SUMMARY:
Sodium chloride, in the presence of ammonium hydroxide, forms sodium
hydroxide, ammonia gas and water. Sodium hydroxide absorbs the
carbon dioxide gas to form sodium bicarbonate. Alcohol does not
react chemically with any of the above compounds, but is used in
this experiment to change the dissolving capacity of water making
sodium bicarbonate less soluble in the mixed solvent than in water.
EXPERIMENT No. 347 Hydrolysis Of Sodium
Bicarbonate
(CL-33, CL-44, CL-55, CL-66, CL-77)
APPARATUS:
Sodium bicarbonate, phenolphthalein, test tube, candle.
PROCEDURE:
Place one measure of sodium bicarbonate and one drop of
phenolphthalein in a test tube one quarter full of water. Shake test
tube and note the color of solution. Heat solution to boiling for a
few minutes. Note the change of color due to the hydrolysis of
sodium bicarbonate.
When sodium bicarbonate and hydrochloric acid
are mixed in the proper proportions, carbon dioxide gas is
liberated.
Because baking soda generates carbon dioxide
gas under certain conditions, it is used in bakeries to "raise"
bread. It is also employed to make carbon dioxide gas in certain
types of fire extinguishers.
POTASSIUM COMPOUNDS
The compounds of potassium are quite like the
corresponding sodium compounds but are more active. Potassium is
important to plant life, and is thus used principally to make
fertilizers.
EXPERIMENT No. 348 Preparation Of Potassium
Hydroxide
(CL-44, CL-55, CL-66, CL-77)
APPARATUS:
Potassium chloride, calcium oxide, sodium carbonate, test tubes.
PROCEDURE:
Prepare a solution of sodium hydroxide as explained in Experiment
344. Dissolve two measures of potassium chloride in another test
tube one quarter filled with water. Mix the two solutions and add
one drop of phenolphthalein.
SUMMARY:
Sodium hydroxide reacts with potassium chloride to form sodium
chloride and potassium hydroxide which colors the solution red.
EXPERIMENT No. 349 Preparation Of Potassium
Carbonate
(CL-33, CL-44, CL-55, CL-66, CL-77)
APPARATUS:
Phenolphthalein, wood ash, test tube, candle, drinking glass.
162 THE
ALKALI METALS
PROCEDURE:
Place six teaspoonsfuls of wood ash in a glass half full of water.
Mix thoroughly with a stirring rod then allow to stand for three
minutes. Filter one quarter test tube of the material and add one
drop of phenolphthalein solution.
SUMMARY:
Wood ash has potassium carbonate as one of its constituents. Adding
phenolphthalein solution results in the pink color due to the basic
properties of potassium carbonate.
EXPERIMENT No. 350 Preparation Of Potassium Acid
Tartrate
(CL-44, CL-55, CL-66, CL-77)
APPARATUS:
Tartaric acid, potassium chloride, test tubes.
PROCEDURE:
Dissolve four measures of tartaric acid in a test tube one quarter
full of water. Dissolve three measures of potassium chloride in
another test tube containing the same amount of water. Add the
tartaric, acid to the potassium chloride and note the white
crystalline precipitate of potassium acid tartrate.
EXPERIMENT No. 351 Identification Of Potassium
(CL-66, CL-77)
APPARATUS:
Nichrome wire, potassium chloride, alcohol lamp.
PROCEDURE:
Place one measure of potassium chloride on a clean sheet of paper.
Moisten the nichrome wire and dip it into the potassium chloride.
Place the wire in the non-luminous part of the flame. Potassium
compounds color the non-luminous flame violet. (Sodium may obscure
the violet color but by viewing the flame through cobalt blue glass
the violet color can be seen easily).
"The Science Notebook"
Copyright 2008-2018 - Norman Young