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  Lionel Chem-Lab - Chapter 9

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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  In addition, much of the information contained in this book about chemistry and other subjects is outdated and some of it is inaccurate.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 137 - 140

CHAPTER IX

BORON AND THE BORATES

The element boron, a gray solid, is not very useful in the pure state, although its compounds are of the greatest importance. Found in southern California in the form of the mineral colemanite, it is the source of many commercial products such as boric acid and borax.

Boric acid is a white solid, slippery to the touch, used principally as an antiseptic and in medicines. Borax, the most important compound of boron, consists chiefly of boric acid and sodium hydroxide. It is known technically as sodium tetraborate.

The chemist finds borax very useful because when heated it froths up and melts into a clear glass. Certain metallic oxides dissolved in melted borax often color the glass with characteristic tints. Thus, small borax beads are used in testing for the presence of such metals. A number of flame color tests using borax beads will be found beginning with Experiment No. 491.

EXPERIMENT No. 269 How To Make Borax

(CL-44, CL-55, CL-66, CL-77)

APPARATUS: Boric acid, test tube and sodium carbonate.

PROCEDURE: Dissolve three measures of boric acid in a test tube half full of water and heat to boiling point. Add two measures of sodium carbonate and again heat to boiling point. Allow contents to cool and note the borax crystals.

EXPERIMENT No. 270 Making Boric Acid from Borax

(CL-33, CL-44, CL-55, CL-66, CL-77)

APPARATUS: Sodium borate (borax), sodium bisulfate, alcohol lamp or candle and two test tubes.

PROCEDURE: Place seven measures of sodium borate in a test tube one-fourth full of water and heat to dissolve. Put five measures of sodium bisulfate in another test tube one-quarter full of water and heat to dissolve. Pour this into the sodium borate solution and then cool by holding the test tube under running water. Note the gradual formation of white crystals.

SUMMARY: Boric acid is often prepared by treating a strong hot solution of borax with an acid from which hydrogen is obtained

137


138 BORON AND THE BORATES

Boric acid is not very soluble in water and consequently crystallizes on cooling.

EXPERIMENT No. 271 Testing For Boric Acid

(CL-44, CL-55, CL-66, CL-77)

APPARATUS: Boric acid, alcohol, heating spoon, test tube, alcohol lamp or candle.

PROCEDURE: Dissolve two measures of boric acid in a test tube one third full of alcohol. Pour some of this into the measuring spoon and ignite it. Note the bright green color of the flame.

SUMMARY: A solution of boric acid and alcohol burns with a green flame. This is a standard test for boric acid.

EXPERIMENT No. 272 Turmeric Paper Used To Detect Boric Acid

(CL-55, CL-66, CL-77)

APPARATUS: Boric acid, test tube and turmeric paper.

PROCEDURE: Place three measures of boric acid in a test tube half full of water and heat to dissolve. Dip some turmeric paper in the solution and allow to dry, using heat if necessary. Note the red color of the paper.

SUMMARY: Boric acid solution poured on turmeric paper turns red when dry. This also is used as a test for boric acid.

EXPERIMENT No. 273 Testing Talcum Powder For Boric Acid

(CL-11, CL-22, CL-33, CL-44, CL-55, CL-66, CL-77)

APPARATUS: Talcum powder, alcohol, heating spoon, test tube,alcohol lamp or candle.

PROCEDURE: Place two measures of talcum powder in a test tube one third full of alcohol and shake to dissolve. Pour some of this in the measuring spoon and ignite it. If the flame is green, the talcum powder contains boric acid. Boric acid is sometimes used in talcum powder because of its mild antiseptic qualities.

EXPERIMENT No. 274 Testing Boric Acid For Acidity

(CL-44, CL-55, CL-66, CL-77)

APPARATUS: Boric acid, blue litmus paper and test tube.

PROCEDURE: Dissolve by heating three measures of boric acid in a test tube half full of water. Dip some blue litmus paper into this and note the red color change.

SUMMARY: Although it has an acid reaction, the water solution of boric acid is very weak and scarcely affects the blue litmus paper.

LIONEL CHEM-LAB 139

EXPERIMENT No. 275 Preparation Of Aluminum Borate

(CL-33, CL-44, CL-55, CL-66, CL-77)

APPARATUS: Aluminum sulfate, sodium borate and test tube.

PROCEDURE: Place three measures of aluminum sulfate in a test tube one half full of water and shake to dissolve. Put two measures of sodium borate in another test tube one quarter full of water and shake to dissolve. Carefully mix the solutions and note the heavy gray-white precipitate.

SUMMARY: The heavy gray precipitate is aluminum borate.

EXPERIMENT No. 276 Calcium Borate

(CL-33, CL-44, CL-55, CL-66, CL-77)

Repeat Experiment No. 275 substituting calcium chloride for aluminum sulfate.

SUMMARY: Sodium borate or borax is sometimes used in the home to soften water. The above reaction shows how calcium is removed by reacting with the borate radical and settling out as the white precipitate of calcium borate.

EXPERIMENT No. 277 Chromium Borate

(CL-44, CL-55, CL-66, CL-77)

Repeat Experiment No. 275 substituting chrome alum for aluminum sulfate. The green precipitate is chromium borate.

EXPERIMENT No. 278 Cobalt Borate

(CL-33, CL-44, CL-55, CL-66, CL-77)

Repeat Experiment No. 275 substituting cobalt chloride for aluminum sulfate.

SUMMARY: Cobalt chloride reacts with sodium borate to form the soluble salt, sodium chloride, and the pinkish blue precipitate, cobalt borate.

EXPERIMENT No. 279 Copper Borate

(CL-55, CL-66, CL-77)

Repeat Experiment No. 275 substituting copper sulfate for aluminum sulfate. The blue precipitate is copper borate.

EXPERIMENT No. 280 Ferric Borate

(CL-33, CL-44, CL-55, CL-66, CL-77)

Repeat Experiment No. 275 substituting ferric ammonium sulfate for aluminum sulfate. The heavy golden brown precipitate is ferric borate.

EXPERIMENT No. 281 Ferrous Borate

(CL-55, CL-66, CL-77)

Repeat Experiment No. 275 substituting ferrous ammonium sulfate for aluminum sulfate. The green precipitate is ferrous borate.


140 BORON AND THE BORATES

EXPERIMENT N0. 282 Manganese Borate

(CL-33, CL-44, CL-55, CL-66, CL-77)

Repeat Experiment No. 275 substituting manganese sulfate for aluminum sulfate. The white precipitate is manganese borate.

EXPERIMENT N0. 283 Magnesium Borate

(CL-66, CL-77)

Repeat Experiment No. 275 substituting magnesium sulfate for aluminum sulfate. The white precipitate is magnesium borate.

EXPERIMENT N0. 284 Strontium Borate

(CL-33, CL-44, CL-55, CL-66, CL-77)

Repeat Experiment No. 275 substituting strontium chloride for aluminum sulfate. The heavy white precipitate is strontium borate.
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