The Science Notebook
  Lionel Chem-Lab - Chapter 4

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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  In addition, much of the information contained in this book about chemistry and other subjects is outdated and some of it is inaccurate.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 58 - 78

58 THE STORY OF WATER

forms of water

The three familiar states of water--liquid, gas, and solid. Upper left is an example of the liquid state. Upper right shows water in a gaseous state, Lower left, and the microphotograph of the snowflake made by the General Electric Laboratories, show water in a solid state.

CHAPTER IV

The Story of Water

Water is as essential to life as air and of all the many chemical compounds available to man, it is certainly the most common, the most abundant and the most useful. It is a compound of two gases, hydrogen and oxygen, and has the well-known formula H20. It covers approximately three-fourths of the earth’s surface, mostly in the form of our great seas and oceans, some of which extend to depths of over five miles.

Both plants and animals consist of from 60% to 95% water. The human body itself is approximately 70% water.

In our study of the air and atmosphere, we observed that the air contains a large amount of water in the form of vapor. In, this form, water controls weather conditions. Rain, snow and other atmospheric precipitation regulate the productivity of the soil, the habits and behavior of people, and in fact, influence to a large extent the progress of civilization. This is how important water is to us.

PROPERTIES OF WATER

Absolutely pure water has neither color, taste nor odor. Probably you have noticed that the water in oceans, lakes and rivers sometimes has a blue or green color. This is due chiefly to the effect of sunlight, the presence of micro-organisms and to mineral and other substances.

EXPERIMENT No. 85 Color And Clarity Of Water

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

APPARATUS: Test tube and paper.

PROCEDURE: Hold a test tube filled with faucet water against a large sheet of white paper. Note whether the water is clear and colorless.

SUMMARY: Water in small quantities is colorless unless impurities are present.

EXPERIMENT No. 86  Testing Water For Odor

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

APPARATUS: Test tube, candle or alcohol lamp.

59


60 THE STORY OF WATER

PROCEDURE: Fill a test tube about half full of water. Shake well, noting any odor which may be present. Heat carefully and smell the water again.

SUMMARY: In most cases, no odor will be present in the water either before or after heating although sometimes heat will liberate gaseous compounds dissolved in the water. Under these circumstances, an odor may be detectable.

DEGREES OF PURITY

Water which falls as rain, snow and other precipitation is the purest form of water found in nature, but is not entirely pure, due to the presence of dust particles and small traces of mineral and organic matter. In the following experiments only in certain cases will definite reactions be noticed because of the high degree of purity found in most drinking water.

EXPERIMENT No. 87 Testing Water For Solid Matter

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

APPARATUS: Beaker or saucer, candle or alcohol lamp.

PROCEDURE: Fill a beaker about half full of water. Heat gently until the water evaporates. Examine the dry beaker and note whether any residue is left.

SUMMARY: If a thin residual coating is left after the water evaporates, it is due to solid matter dissolved in the water.

EXPERIMENT No. 88 Testing Water For Acidity

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

APPARATUS: Blue litmus paper and test tube.

PROCEDURE: Fill a test tube half full of water. Drop in a strip of blue litmus paper. Note whether a change in color occurs.

SUMMARY: Water in its natural state often dissolves decayed organic substances. In most cases, no color reaction in the litmus paper occurs. If the blue litmus paper turns red, it is due to traces of acid in the water.

EXPERIMENT No. 89 Testing Water For Alkalinity

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

APPARATUS: Test tube and phenolphthalein solution.

PROCEDURE: Add a few drops of phenolphthalein solution to a test tube half full of water. Note whether there is any change in color.

SUMMARY: The indicator, phenolphthalein, turns red in the presence of bases.

EXPERIMENT No. 90 Sulfates In Water

(CL-33, CL-44, CL-55, CL-66, CL-77) 

LIONEL CHEM-LAB 61

APPARATUS: Strontium chloride and test tube.

PROCEDURE: Dissolve one measure of strontium chloride in a test tube half full of water. Shake well and allow to stand for a few minutes. Note whether or not a precipitate appears.

SUMMARY: If a sulfate is present, the solution becomes turbid and a precipitate, strontium sulfate, will appear.

EXPERIMENT No. 91 Iron In Water

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

APPARATUS: Sodium ferrocyanide and test tube.

PROCEDURE: Dissolve one measure of sodium ferrocyanide in test tube half full of water. Shake well and allow to stand for awhile.  Observe any color changes.

SUMMARY: If iron is present in water, a blue color appears when sodium ferrocyanide is added.

EXPERIMENT No. 92 Hydrogen Sulfide In Water

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

APPARATUS: Sulfide test paper and test tube.

PROCEDURE: Fill a test tube half full of water. Insert a strip of sulfide test paper. Note any color changes on the paper.

SUMMARY: When moistened sulfide test paper (lead acetate) is brought into contact with hydrogen sulfide, the paper becomes blackened because of the formation of lead sulfide. This is a test for hydrogen sulfide.

EXPERIMENT No. 93 Testing Water For Carbon Dioxide

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

APPARATUS: Calcium oxide and two test tubes.

PROCEDURE: Place one measure of calcium oxide in a test tube half filled with water. Shake this solution of lime water well and allow the undissolved particles to settle out. Pour a few drops of the clear solution into a test tube half full of water. Note whether or not any changes occur.

SUMMARY: If water contains carbon dioxide gas or a carbonate, the addition of limewater will bring about a cloudy and turbid solution. To get a more positive reaction, repeat experiment using charged (soda) water.

In the laboratory, the purest form of water is obtained by distillation.  Distilled water is used in automobile storage batteries and in chemical laboratories because mineral salts normally found in water interfere with the exactness required of certain chemical analyses.

Water can be distilled very easily by setting up a simple laboratory


62 THE STORY OF WATER

apparatus. The water to be distilled is placed in a test tube and heated. The vapors are passed through the delivery tube and condensed into a test tube immersed in water.

EXPERIMENT No. 94 Distillation Of Water

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

distilling water

FIGURE 11

APPARATUS: Copper sulfate, gas delivery tube and stopper, two test tubes, glass, alcohol lamp or candle.

PROCEDURE: Place one measure of copper sulfate into a test tube half filled with water. Shake to dissolve and note the blue color. Insert the gas delivery tube and stopper into the test tube and place the other end of the delivery tube in an empty test tube immersed in a glass of cold water. Hold the test tube containing the copper sulfate solution over a flame and heat to boiling. Note the condensation of clear water in the other test tube.

SUMMARY: Water turns to steam when it is heated, passes through the delivery tube and condenses as water again when it reaches the cool test tube. Copper sulfate has a higher boiling point than water, therefore it remains behind in the first test tube.

Neither boiling nor filtration results in pure water although by first boiling the water, then filtering to remove the suspended matter, it will be improved.


LIONEL CHEM-LAB 63

PURIFICATION OF DRINKING WATER

In addition to mineral impurities, we also have to contend with the problem of organic matter found in natural waters which may contain disease-producing organisms known as bacteria.

There is a great danger of contamination to the water supplies of our large cities because of the increasing population and the fact that the water is usually obtained from nearby lakes and rivers.

In order to prevent the spread of such a disease as typhoid fever by drinking water, modern cities now purify their entire water supply.  We have already discussed purification of water by distillation and boiling, but it is obvious that such laboratory methods would not be practical on a large scale. For this reason, the chlorine method of treatment, sand filtration and aeration are the methods most widely used either individually or jointly. Chlorination of drinking water is discussed more fully in our chapter on Chlorine.


water purification

Wallace and Tiernan Co., Inc.

An illustration of a modern chlorination plant showing the instruments used to purify urban drinking water supplies and for decontaminating sewage.

EXPERIMENT No. 95 Sand Filtration

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

APPARATUS: Fine-mesh tea strainer, sand and a glass.

64 THE STORY OF WATER

PROCEDURE: Fill the strainer with fine sand and place the strainer in the mouth of the glass. Prepare some muddy water and pour it over the sand. Note the color of the water as it drops into the glass.

SUMMARY: The mud which remains in suspension in the water is removed as the liquid filters through the sand. The filtrate will be quite clear, any discoloration being due to foreign matter which cannot be removed by the sand filter.

EXPERIMENT No. 96 Another Method Of Purifying Water

(CL-66, CL-77)

APPARATUS: Aluminum sulfate, calcium hydroxide, test tube.

PROCEDURE: Dissolve a half measure of aluminum sulfate in a test tube three quarters full of muddy water. Add one-half measure of calcium hydroxide. Shake well and set aside for a few minutes. Note the clarity of the water.

SUMMARY: The suspended matter in the water can be gathered into larger particles by introducing a little of the jelly-like precipitate of aluminum hydroxide formed by the reaction of aluminum sulfate and calcium hydroxide. The aluminum hydroxide settles out along with the particles and thus the water becomes clear by the process of coagulation.

HARD WATER AND SOFT WATER

We have already seen that water contains more or less mineral and organic matter which it receives from rocks and soil. This mineral material, composed principally of calcium and magnesium, causes much trouble and expense. Soap does not lather well in water having a high mineral content; there is a waste of soap and washing becomes difficult. Also these minerals settle out in the hottest parts of boilers and pipes forming a stone-like coating which prevents full transfer of heat from the fire. This is not only a nuisance and expensive to remove, but sometimes results in boiler explosions.

EXPERIMENT No. 97 Testing Water For Hardness

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

APPARATUS: Soap shavings and two test tubes.

PROCEDURE: Dissolve a small piece of soap in a test tube half full of warm water. Add a few drops of this soap solution to a second test tube full of water. Shake well and note whether there is any lather.

SUMMARY: If the water lathers rapidly, the water is soft but if suds form very slowly and a precipitate appears, the water is hard.

EXPERIMENT No. 98 The Reaction Of Soap With Hard Water

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

APPARATUS: Calcium chloride and two test tubes.

LIONEL CHEM-LAB 65

PROCEDURE: Dissolve one half measure of calcium chloride in a test tube half full of water. Prepare a soap solution by dissolving a small piece of soap in a second test tube half filled with warm water.  Add a few drops of the soap solution to the first test tube which now contains hard water. Note the change in the solution.

SUMMARY: The soap solution curdles in the presence of water made hard by the addition of calcium chloride. Hard water is not suitable for washing in the household or laundry because too much soap has to be dissolved before the right amount of lather is obtained. Until the salts which cause the hardness are precipitated, the water is not suitable for washing.

Chemists differentiate between temporary hardness and permanent hardness.

Temporary hard water is frequently found in the spring water of limestone regions. This water contains such impurities as calcium bicarbonate and magnesium bicarbonate. Temporary hard water can be softened by boiling, but on a large scale this is not practical so a certain amount of calcium hydroxide is used as a catalyst to precipitate insoluble calcium carbonate.  The purpose (as in boiling) is to convert the soluble bicarbonate to insoluble carbonates.

Permanent hard water usually contains calcium sulfate or chloride in solution. Sometimes also magnesium and iron salts are present. The reason it is called "permanent" is because it cannot be softened by boiling. When washing soda is added, however, some of the impurities are precipitated.

Softening water on a large scale can be done very efficiently by the Permutite Process. Permutite is a complex substance composed principally of sodium, silicon and aluminum.

ELECTROLYSIS OF WATER

We have mentioned that water is composed of hydrogen and oxygen in the proportion of two parts of hydrogen to one of oxygen. This can be proved by a process known as electrolysis, that is, passing an electric current through the water.


electrolysis setup

FIGURE 12

EXPERIMENT No. 99 Electrolysis Of Water

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

APPARATUS: Three dry cells, two test tubes, cardboard, a pan or any small household utensil, copper wire.

66 THE STORY OF WATER

PROCEDURE: Connect the cells in series using insulated copper wire as shown in the diagram. Wind the remaining ends of wire around the carbon rods. Half fill the pan with water. Fill a test tube with water, place your finger over the top and invert it in the pan removing your finger when the mouth of the tube is in the water. Repeat this procedure with the other test tube. Insert the carbon rods into the two test tubes. Place ten measures of sodium bisulfate in the pan to aid the passage of an electric current through the water. Hold the test tubes erect by using a strip of cardboard as a brace. Note the rising gas bubbles from the carbon posts, hydrogen gas from the negative terminal, and oxygen from the positive terminal. After a quantity of hydrogen and oxygen has been collected, remove the carbon rods while keeping the test tubes under water. Note the volume of gas in both tubes. Remove the tube containing the oxygen and quickly insert a glowing splint. Note how the splint becomes brighter (it may even burst into flame). Remove the tube containing the hydrogen and cautiously place the mouth of the tube near the flame. Note the slight
explosion.

SUMMARY: Decomposition of a compound by the use of electrical energy is called electrolysis.

After the apparatus for the experiment has been set up in accordance with the diagram, the electric current passing through the water acts to separate it into the two gases of which it is formed. When water and other substances in solution are decomposed by electric current the chemists explain this action by the theory of ionization.

SOLUTIONS

In many of our experiments, we have made solutions. What is a solution?

A solution is the result of dissolving one substance (either solid, liquid or gas) in another substance, usually a liquid. Although a solution is of uniform consistency, the proportion of the ingredients may vary greatly and for this reason we classify solutions as either dilute (having a small amount of dissolved substance) or supersaturated.

EXPERIMENT No. 100 A Supersaturated Solution

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

APPARATUS: Sodium thiosulfate, piece of cotton, test tube, candle or alcohol lamp.

PROCEDURE: Fill a test tube about one-third full of sodium thiosulfate. Add a few drops of water and heat. When the solution is about to boil, set it aside to cool, plugging the mouth of the tube with cotton.  Do not stir or shake while cooling. Remove the cotton and add a small crystal of sodium thiosulfate and note the change.

LIONEL CHEM-LAB 67

SUMMARY: A supersaturated solution is one in which the quantity of the substance dissolved is more than what the liquid can hold at ordinary temperatures. Such a solution is very unstable as evidenced by the way crystals of sodium thiosulfate begin to form when just one additional crystal is dropped into the tube. The same effect can be obtained by shaking or stirring.

EXPERIMENT No. 101 How A Solution Aids Chemical Reactions

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

APPARATUS: Sodium bicarbonate (or sodium carbonate), tartaric acid, paper and test tube.

PROCEDURE: Mix on a sheet of paper one measure of tartaric acid and one measure of sodium bicarbonate. Note whether any chemical reaction occurs. Place this mixture in a test tube and add a few drops of water. Observe whether a chemical reaction takes place.

SUMMARY: When the chemicals were mixed no reaction took place, but the moment a little water was added, a sizzling reaction set in and gas was evolved. Water was a necessary factor in bringing about a chemical reaction.

EXPERIMENT No. 102 Detecting Moisture

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

APPARATUS: Ferric ammonium sulfate, sodium ferrocyanide, white paper, test tube and cotton.

PROCEDURE: Dissolve three measures of ferric ammonium sulfate in a test tube half filled with water. Immerse some strips of white paper in the solution and allow to dry. Crush a crystal of sodium ferrocyanide and apply it with a bit of cotton to one of the dry strips. Place a drop of water in one corner of this strip and note the blue color.

SUMMARY: When water is added to. a mixture of ferric ammonium sulfate and sodium ferrocyanide, a blue color results. This is often used as a test to detect the presence of water in a compound.

EXPERIMENT No. 103 Removing Salt From A Solution

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

APPARATUS: Table salt, glass and pan.

PROCEDURE: Dissolve one heaping spoonful of salt in a glass one-quarter full of warm water. Pour the contents into a pan and heat carefully on the stove until the water evaporates. Note whether a solid remains. Test the recovered salt by tasting.

SUMMARY: The salt taste proves that the salt has been recovered.  This is not a difficult task because the water can be vaporized while the salt cannot. This also proves that a substance does not necessarily lose its properties by being dissolved in water.

68 THE STORY OF WATER

EXPERIMENT No. 104 A Solvent For Grease

(CL-66, CL-77)

APPARATUS: Carbon tetrachloride and butter.

PROCEDURE: Insert a small portion of butter into a dry test tube.  Add a little carbon tetrachloride. Note that the butter dissolves.

SUMMARY: Carbon tetrachloride is a good solvent for fats, oils, gums and resins and thus is used extensively as a cleaning fluid.

EXPERIMENT No. 105 Temperature Affects Solubility Of Gas

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

APPARATUS: Test tube and candle or alcohol lamp.

PROCEDURE: Fill a test tube half full of water. Hold the test tube over a flame and note the appearance of gas bubbles. Continue heating until the water boils, then cool by running cold water on the test tube. Heat again and note whether gas bubbles form. Repeat this process several times.

SUMMARY: In the first few heatings the gaseous compounds are removed from the water, proving that the solubility of gas diminishes with an increase in temperature. However, the lower the temperature of the liquid, the greater the solubility of the gas. For a more positive reaction, repeat the experiment substituting charged (soda) water.

OTHER TYPES OF SOLUTIONS

EXPERIMENT No. 106 Boiling A Solution Removes Gas

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

APPARATUS: Ammonium hydroxide (or household ammonia), phenolphthalein solution, test tube, candle or alcohol lamp.

PROCEDURE: Place a drop of ammonium hydroxide in a test tube one-quarter full of water. Add a drop of phenolphthalein solution and note the color change. Heat carefully until the liquid boils and again note the color change.

SUMMARY: Ammonium hydroxide in water gives a basic reaction.  Consequently, it becomes red when phenolphthalein is added. When the ammonia is heated, the ammonia gas is driven off with the result that the solution loses its alkalinity and becomes colorless.

EXPERIMENT No. 107 Liquids Soluble In Each Other

(CL-66, CL-77)

APPARATUS: Carbon tetrachloride, glycerine and two test tubes.

PROCEDURE: Add a few drops of carbon tetrachloride to a test tube containing a little water. Shake vigorously and note whether the carbon tetrachloride dissolves. Place a few drops of glycerine in the other

LIONEL CHEM-LAB 69

test tube containing water. Shake well and note whether the glycerine dissolves.

SUMMARY: There are times when one liquid will not dissolve in another as is the case with water and carbon tetrachloride. Whenever this occurs, the solvents settle out in individual layers. Glycerine, however, is soluble in water.

FILTERING SUSPENSIONS

We have mentioned that a solution is a uniform mixture, but a suspension is also a mixture of a solid and a liquid. In the case of a suspension, however, the solid particles settle out on standing. When finely powdered sand or clay (insoluble in water) is well shaken or stirred in water, a turbid liquid is obtained. This is an example of a suspension. The solid sand does not dissolve and after the mixture has stood for a while the sand will slowly settle to the bottom leaving the clear liquid. This solid can be removed by the process of filtration.

HOW TO FILTER

To filter a solution you must use your glass funnel and filter paper. Filter paper comes in round sheets and it must be folded so that it will fit closely into the glass funnel. Do this by folding a sheet of filter paper through the center and then folding it again into quarters. After this has been done, it can be made into a cone and set into the top of the funnel. You are now ready to pour the solution into the funnel.

EXPERIMENT No. 108 Separating A Soluble From An Insoluble

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

APPARATUS: Ammonium chloride, sulfur, test tube and filter paper.

PROCEDURE: Mix five measures of ammonium chloride and two and a half measures of sulfur in a test tube. Add water up to the three-quarter mark and shake. Pass this through a filter and collect the filtrate in a saucer. Heat the solution slowly to evaporate it. Unroll the filter paper and allow contents to dry. Check these against the original chemicals.

SUMMARY: The ammonium chloride was soluble in the water whereas the sulfur was not. Thus, the ammonium chloride passed through the filter and was collected in solution as a filtrate. When this is heated, the water is drawn off and the ammonium chloride remains as a solid in the original state. By drying the filter paper you will be able to recover the sulfur as it was originally.

TEMPERATURE

We have already mentioned that the freezing point of water is 32° F. (Fahrenheit) and the boiling point is 212° F.

70 THE STORY OF WATER

The chemist measures the temperature of a substance with a thermometer, usually marked off in the degrees of the Centigrade scale. According to the Centigrade scale, water freezes at 0° C. and boils at 100° C.  However, as most boys are more familiar with the Fahrenheit scale, the Lionel Chem-Lab thermometer is graduated according to this scale from 20° below zero to 230° above zero, or 18° above the boiling point of water. This thermometer is suitable for taking temperature readings in any of our experiments.

If we make up a solution, by dissolving some substance such as salt in water, this very definitely affects the freezing and boiling points. Likewise, it seems that solids dissolve more readily in a warm liquid than they do at a cooler temperature. Sugar, for example, is more soluble in hot water than in cold. Salt, on the other hand, will dissolve nearly as well in cold as in hot water.

Certain important changes take place while a solution is being formed.  When some solids are dissolved, energy is absorbed and the temperature of the solution goes down. For example, in preparing a freezing mixture, when we mix ice and salt, some of the ice melts and the salt dissolves in the water.  Both of these processes result in the absorption of heat, and thus the temperature will fall below the normal freezing point of water. The salt water does not freeze because its freezing point is lower than that of pure water.

In the old fashioned method of making ice cream, the cream was placed in a metal container around which was packed a mixture of salt and ice. The faster ice melts, the greater the degree of coldness. Therefore, to accelerate the freezing of the cream, the salt was used to melt the ice more quickly.

EXPERIMENT No. 109 Comparing Boiling Points

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

APPARATUS: Salt, two test tubes, candle or alcohol lamp.

PROCEDURE: Prepare a salt solution by dissolving fifteen measures of salt in a test tube three-quarters full of water. Fill a second test tube three-quarters full of water. Heat both test tubes until the contents boil. Note that one solution boils sooner than the other.

SUMMARY: When salt is added to water, the boiling is hastened.

EXPERIMENT No. 110 Comparing Freezing Points

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

APPARATUS: Cracked ice, glass, two test tubes and salt.

PROCEDURE: Prepare a freezing mixture by adding one third of a glass of salt to a glass filled with cracked ice. Dissolve fifteen measures of salt in a test tube half full of water. Fill a second test tube half full of water. Place both test tubes in the freezing mixture. Note that the plain water will freeze before the salt solution.

LIONEL CHEM-LAB 71

SUMMARY: When salt is added to water, its freezing point is lowered.

EXPERIMENT N0. 111 Supercooled Water

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

APPARATUS: Glass, cracked ice, salt, test tube, thermometer.

PROCEDURE: Prepare a freezing mixture by adding one quarter of a glass of salt to a glass three fourths full of cracked ice. Fill a test tube one quarter full of water. Carefully insert the tube into the freezing mixture. Check temperature after a short time. Now drop a piece of ice into the test tube. Again check the temperature at which freezing occurs.

SUMMARY: A Supercooled solution is one which has been cooled below its freezing point without becoming solid. This occurs only in a solution which has not been disturbed during the cooling process. However, the solution will freeze immediately if the test tube is moved or a piece of ice added.

EXPERIMENT No. 112 Another Effect Of Temperature On Solubility

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

APPARATUS: Calcium oxide, two test tubes, candle or alcohol lamp.

PROCEDURE: Add one measure of calcium oxide to a test tube half filled with water. Shake vigorously and then allow the undissolved particles to settle out. Carefully pour the clear solution into another test tube and heat over a flame. Note change in the appearance of the clear solution.

SUMMARY: Calcium oxide is one of the few chemicals which are more soluble in cold water than in hot. Consequently, some of the particles of calcium oxide come out of the solution as it is heated and cause the liquid to become cloudy.

EXPERIMENT No. 113 Negative Heat Of Solution

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

APPARATUS: Test tube, ammonium chloride (or sodium thiosulfate) and thermometer.

PROCEDURE: Take the temperature of a test tube half filled with water. Add one half spoonful of ammonium chloride. Note that the temperature falls.

SUMMARY: Some compounds such as ammonium chloride have the ability to absorb heat from the water in which they are dissolved, consequently cooling the water. Compounds of this type are said to have a negative heat of solution.

EXPERIMENT No. 114 Positive Heat Of Solution

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


72 THE STORY OF WATER 

APPARATUS: Test tube, magnesium sulfate or calcium chloride, thermometer.

PROCEDURE: Take the temperature of a test tube half full of water.  Add a half spoonful of magnesium sulfate. Note the rise in temperature.

SUMMARY: Some compounds such as magnesium sulfate give off heat to the water in which they are dissolved.  Compounds of this type have a positive heat of solution.

SPECIFIC GRAVITY

The term specific gravity sounds formidable but it merely means that one substance is more dense than another. Lead is more dense than water; lead weighs more than water. Therefore, density is the weight of a substance in a certain unit of volume.

EXPERIMENT No. 115 Specific Gravity

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

APPARATUS: Sodium salicylate, ferric ammonium sulfate, piece of tissue paper and a drinking glass.

PROCEDURE: Dissolve two measures of sodium salicylate in a glass three fourths full of water. Place one measure of ferric ammonium sulfate in the tissue paper and fold the corners so that the chemical is completely covered by the paper. Insert this in the glass containing the sodium salicylate and set aside. Note the streamer formation and the sinking of the red liquid.

SUMMARY: When the sodium salicylate solution passes through the tissue paper it reacts with the ferric ammonium sulfate to form the beautiful red streamers of ferric salicylate. These streamers sink to the bottom because the specific gravity has been changed.

The gram is the unit of weight generally used when dealing with solids and liquids, and the cubic centimeter (cc.) is the unit of volume.  Specific gravity is defined, therefore, as the weight in grams of 1 cc. of the substance.  Since 1 cc. of water weighs 1 gram, it can be seen readily that the number which represents the density of other solids and liquids also represents their relative weights as compared with water.

SURFACE TENSION

EXPERIMENT No. 116 Surface Tension

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

APPARATUS: Rubber band, dish, toothpick and oil.

PROCEDURE: Float a thin rubber band in a dish of water, making certain that it does not touch the sides. By means of a toothpick dipped in oil, pierce the surface of the water inside the rubber band. Do it


LIONEL CHEM-LAB  73

again and note the results. Repeat, this time piercing the water outside of the band. Again note the results.

SUMMARY: When oil is applied to the water area within the rubber band, the surface tension of this area becomes less than the surface of the water surrounding the rubber band. Thus the band is stretched away from its center. When the oil is applied in the same fashion to the liquid outside the band, the surface tension outside becomes less than the surface tension inside and the rubber band returns to its original shape.

EXPERIMENT N0. 117 A Needle Floats On Water

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

APPARATUS: Saucer and sewing needle.

PROCEDURE: Carefully place a small sewing needle on the surface of the water in a saucer. Note whether the needle has a tendency to sink.

SUMMARY: The needle floats because the surface film, which has not been pierced or distorted, supports it.

EXPERIMENT No. 118 Destroying Surface Tension

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

APPARATUS: Saucer, sodium carbonate, glass, a needle, soap.

PROCEDURE: Dissolve several measures of sodium carbonate in a saucer half full of water. Carefully place the needle on the surface of the solution and touch the water on each side of the needle with soap. Observe whether the needle sinks or floats.

SUMMARY: Soap in this particular case destroyed the surface film allowing the needle to sink.

EXPERIMENT No. 119 Rise Of Water In Capillary Tubes

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

APPARATUS: Glass tube, candle or alcohol lamp, dish and file.

PROCEDURE: Heat the middle section of the glass tube over the flame rolling it back and forth between your fingers. Remove from the flame when glass becomes soft and pull carefully in opposite directions to decrease the diameter of the central portion of the tube. Cut this thin section out with a file. Insert it in the bowl of water and note the rise of the solution in the tube.

SUMMARY: The water in the tube rises above the surface of the water in the dish. This demonstrates capillary action.

EXPERIMENT No. 120 Capillary Action In A Lump Of Sugar

(CL-66, CL-77)

APPARATUS: Mixed dyes, teaspoon, lump of sugar and saucer.

74 THE STORY OF WATER

PROCEDURE: Add one half measure of mixed dyes to a saucer containing a few teaspoonfuls of water. When a uniform color exists, stand a lump of sugar upright in the liquid. Note the rise of color in the lump of sugar.

SUMMARY: The colored solution aids in detecting the rise of water.  This is a form of capillary action because the spaces between the grains of sugar act as capillary tubes.

DIFFUSION

Diffusion means the gradual dispersion of the particles of one substance among those of another. The four principal types of diffusion are: diffusion of liquids, diffusion of substances in solution, diffusion of gases and diffusion of solids.

EXPERIMENT No. 121 Diffusion Demonstrated

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

APPARATUS: Sodium silicate solution, tall glass and cobalt chloride, test tube.

PROCEDURE: Fill a test tube one-quarter full of sodium silicate solution. Add water to the half way mark and stir thoroughly. Add three or four crystals of cobalt chloride. Note the growth. Float a cobalt chloride crystal on the surface of the liquid. Note the growth toward the bottom of the glass.

SUMMARY: The swelling of the cobalt chloride crystals is due to their reacting with the sodium silicate solution to form cobalt silicate.

EXPERIMENT No. 122 Color Uniformity In A Solution

(CL-66, CL-77)

APPARATUS: Mixed dyes and glass.

PROCEDURE: Add a very small amount of mixed dyes to a glass half filled with water. Set aside and note whether a uniform color finally sets in.

SUMMARY: The dye diffuses through the liquid until the solution has a uniform color. Ordinarily a solid when dissolved tends to distribute itself uniformly through the liquid so that every part of the solution has the same concentration. This goes on very slowly unless it is speeded by stirring or shaking. In the case of some colored solids dissolved in water, weeks may go by before a uniform color is obtained.

EXPERIMENT No. 123 Diffusion Of Red Ferric Salicylate

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

APPARATUS: Ferric ammonium sulfate, sodium salicylate and test tube.

PROCEDURE: Place a few crystals of ferric ammonium sulfate in a test tube two thirds full of water. Carefully add one measure of

LIONEL CHEM-LAB 75

sodium salicylate. Note the reaction. Set aside for a few days and observe the uniformity of the red solution.

SUMMARY: The red ferric salicylate goes to the bottom of the liquid because of specific gravity. However, after standing for a long time, the red portion diffuses through the liquid and results in a uniform color.

WATER OF CRYSTALLIZATION

Many substances combine chemically with water to form compounds called hydrates. These compounds will give up or lose water by simple exposure to the air or application of heat. Water occurring and behaving in compounds in this interesting way is known as water of crystallization or hydration.

EXPERIMENT No. 124 Changing The Color Of A Solution

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

APPARATUS: Cobalt chloride, test tube, candle or alcohol lamp.

PROCEDURE: Add three measures of cobalt chloride to a test tube half full of water. Heat gently and note color change. Allow tube and contents to cool and again observe the change in color.

SUMMARY: Heating the solution drives off the water of hydration of cobalt chloride turning it blue. However, as the solution cools, the cobalt chloride again takes up the water which it has lost and becomes pink.

Many compounds which are soluble in hot water give a visible crystalline precipitate upon cooling. Crystalline washing soda (sodium carbonate) is an example of a compound which behaves in this way.

EXPERIMENT No. 125 Washing Soda Crystals

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

APPARATUS: Washing soda (sodium carbonate), test tube.

PROCEDURE: Place four measures of washing soda in a test tube.  Heat carefully. Note that the water condenses at the mouth of the test tube.

SUMMARY: Washing soda is sodium carbonate plus water of hydration. When heat is applied, the water is driven off and the plain sodium carbonate, which is white in appearance, remains.

Crystals vary in size from those which can only be seen with the aid of a microscope to such massive types as the quartz crystal in California which weighs a ton.

The secret of making better crystals is to permit the solution to cool slowly. Keep this in mind when performing subsequent experiments.


76 THE STORY OF WATER

EXPERIMENT No. 126 Tartaric Acid Crystals

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

APPARATUS: Tartaric acid, beaker or small glass, cardboard, alcohol lamp or candle, test tube.

PROCEDURE: Prepare a saturated solution of tartaric acid by dissolving as much of the chemical as possible in a test tube filled with hot water. Pour the clear liquid into a small glass or beaker. Cool slowly, placing a small piece of cardboard over the mouth of the glass.  Examine crystals for structure and appearance.

EXPERIMENT No. 127 Magnesium Sulfate Crystals

(CL-66, CL-77)

APPARATUS: Magnesium sulfate, alcohol lamp or candle, test tube, beaker or small glass, piece of cardboard.

PROCEDURE: Prepare a saturated solution of magnesium sulfate by dissolving as much of the chemical as possible in a test tube filled with water. Pour the clear liquid into a small glass or beaker. Cool slowly, placing a cardboard over the mouth of the glass. Examine crystals for structure and appearance.

EXPERIMENT No. 128 Sodium Sulfate Crystals

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

APPARATUS: Sodium sulfate, test tube, beaker or small glass, piece of cardboard, alcohol lamp or candle.

PROCEDURE: Prepare a saturated solution of sodium sulfate by dissolving as much of the chemical as possible in a test tube half full of hot water.  Pour the clear liquid into a small glass or beaker.  Cool slowly by placing a cardboard over the mouth of the glass.  Examine crystals for structure and appearance.

EXPERIMENT No. 129 Crystal Formation

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

APPARATUS: Sodium borate, test tube, candle or alcohol lamp.

PROCEDURE: Place ten measures of sodium borate in a test tube one quarter full of water. Boil until the solid dissolves. Set contents aside to cool. Repeat as above but this time cool the contents quickly by inserting the test tube in a glass of water.

SUMMARY: When the solution cools quickly, frost-like crystals begin to form on the walls of the test tube. The slower the cooling process, the better the crystals.

EXPERIMENT No. 130 Formation Of Rock Salt

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

LIONEL CHEM-LAB 77

crystal growing

FIGURE 13

APPARATUS: Small glass, common salt, cardboard, string, weight and stirring rod.

PROCEDURE: Fill a glass about one quarter full of salt. Add water until the glass is three fourths full. Dissolve all the salt by stirring, adding a little more water, if necessary. Suspend a string in the glass by attaching one end to a piece of cardboard resting on top of the glass, and fastening a small weight to the end going into the solution. Cover the glass and set aside for a few days noting any changes which occur from day to day.

SUMMARY: Within s day or two salt crystals will begin to form on the string and the size of these  crystals will increase daily.

EXPERIMENT No. 131 How To Make Rock Candy

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

APPARATUS: Two glasses, string, small weight, cardboard, sugar and stirring rod.

PROCEDURE: Dissolve as much sugar as possible in a small glass half filled with hot water. Stir thoroughly and pour the clear syrupy liquid into another glass. Suspend a string in the glass as in the preceding experiment. Set aside for a few days.

SUMMARY: Within a few days crystals of sugar, commonly called rock candy, will form on the string.

EXPERIMENT No. 132 Frosting Glass With Crystals

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

APPARATUS: Ammonium chloride, glue, test tube, small brush, pane of glass.

PROCEDURE: Place six measures of ammonium chloride and one drop of glue in a test tube containing one half inch of water. Boil until the solid dissolves. Brush the hot liquid on the pane of glass. Note the crystal formation.

SUMMARY: The crystals will appear as soon as the heated liquid has been applied to the glass making it appear as if it were frosted with ice.

78 THE STORY OF WATER

EXPERIMENT No. 133 Efflorescence Demonstrated

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

APPARATUS: Cobalt chloride, heating spoon, candle or alcohol lamp and stirring rod.

PROCEDURE: Observe the color of cobalt chloride when two measures of it are placed in the heating spoon. Heat gently until it becomes blue.  Add a drop of water, stir and once again note the color.

SUMMARY: Cobalt chloride loses its water, or dehydrates, when heated and turns blue. This process is known as efflorescence. Adding a drop of water causes the original pinkish color to return.

EXPERIMENT No. 134 A Cobalt Chloride Barometer

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

APPARATUS: Cobalt chloride, white paper, test tube and a small brush.

PROCEDURE: Prepare a concentrated solution of cobalt chloride by dissolving two measures in a test tube one quarter full of water. Brush this solution on a piece of white paper and allow to dry. Hang the paper in a place where the outdoor air can get at it easily.

SUMMARY: Cobalt chloride is sensitive to moisture in the air. When it acquires a bluish tinge, it usually indicates fair weather ahead, and when it becomes pink, the indication is that dampness has set in or rain is about to fall.

EXPERIMENT No. 135 Deliquescence Demonstrated

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

APPARATUS: Calcium chloride, saucer or watch glass.

PROCEDURE: Place two measures of calcium chloride on a saucer.  Allow it to remain exposed to the air for some time. Examine occasionally and note changes.

SUMMARY: If the air is not too dry, calcium chloride will absorb moisture from it and become wet. This is known as deliquescence.  Calcium chloride is frequently sprinkled on dusty roads and subway tracks to keep the road moist and allow the dust to settle.

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