you obtained. Make a table showing which of the carbon ates tested are soluble in water and which are insoluble. 3. To the other half of the sodium bicarbonate add either dilute hydrochloric or sulfuric acid. Carbon dioxide gas is evolved. Prove this by holding a drop of limewater on a stirring rod in the gas coming from the tube. If the drop becomes milky, carbon dioxide is indicated. Write the equation for the reaction. In like manner test the action of an acid on the other carbonates you obtained. Write the equations for the reactions in each case. All carbonates, when treated with hydrochloric or sulfuric acid, evolve carbon dioxide. This is the test for a carbonate. 4. Test baking soda for a carbonate. What is baking soda? 5. Test washing soda for a carbonate. What is washing soda? 6. Test boiler scale from a teakettle at home for a carbonate. What is boiler scale? 7. Test coral, oyster shell, or any other sea shell for a carbonate. Of what are sea shells composed chiefly? 8. Test limestone for a carbonate. What is limestone? MATERIALS. EXPERIMENT 30 Flames Candles, splints, powdered wood charcoal. A. Candle Flame. 1. Place a lighted candle so that the flame is against a black background and note the different cones in the flame. Draw a diagram showing the different parts of the flame. 2. Test the different cones in the flame with a small splint. Which is the hottest cone? 3. Blow out the flame and hold a lighted splint in the little column of smoke coming from the wick. Explain the result. 4. Candle wax is composed chiefly of carbon and hydrogen. What then are the chief products of combustion when a candle burns in the air? Prove the presence of these products by very simple experiments. B. Bunsen Flame. 1. Draw the diagram of a Bunsen flame. 2. Test the different cones in the flame with small splints. Which is the hottest flame? Hold a splint horizontally in the base of the Bunsen flame for three seconds. Explain the result. 3. Put one end of a glass elbow or glass tube in the inner cone just above the burner tube and light the gas at the end of the glass tube. Raise the tube until it is in the Bunsen flame's second cone. Result? What is the inner cone of the Bunsen flame? . 4. Press the wire screen down in the Bunsen flame. Why does the flame not burn above the screen? Light the gas above the screen. Turn the gas off, then turn it on again and light it above the wire screen held about two inches above the top of the burner. Explain. 5. Shake some powdered wood charcoal into a non-luminous Bunsen flame. Explain the result. Beat some of the chalk dust from a blackboard eraser into a non-luminous flame. Explain the result. 6. Make the Bunsen flame luminous by closing the holes in the tube. Hold a clean, dry evaporating dish in the luminous flame. Why is carbon (lampblack) deposited? Will a non-luminous flame deposit soot? What makes a flame luminous? 7. The flame produced by the burner of the kitchen range is non-luminous. Explain how the burner is constructed to produce this non-luminous flame. Draw a diagram. What advantages has a non-luminous flame over a luminous one in such a range? How could the same gas that is used for lighting purposes in the range be used for lighting the home? PART II SECOND TERM'S WORK IX. COMMON ORGANIC COMPOUNDS AN organic compound is one that contains carbon. Organic chemistry is the study of compounds containing carbon. Carbon monoxide, carbon dioxide, carbonic acid, and the carbonates are organic compounds, but for the sake of convenience, and because of their common occurrence, they are usually studied in inorganic chemistry. The simplest organic compounds are composed of carbon, hydrogen, and oxygen. The more complex compounds found in plant and animal tissues are composed of carbon, hydrogen, oxygen, nitrogen, sulfur, and phosphorus in varying proportions. These complex bodies are usually decomposed when heated, leaving a black residue of carbon. This is called a "charring test" for an organic compound. Some substances, like kerosene, when heated, burn leaving no residue of carbon. Such substances burn with a luminous flame that deposits "soot," which is carbon, upon a cool surface. This is also a test for an organic substance. This is called the "soot test." 66 There are other substances, like alcohol and ether, which neither leave a residue nor deposit "soot" when they burn. If a drop of limewater is held over such a flame, the presence of carbon dioxide may be detected. This test holds good for any organic substance, for carbon dioxide is always formed when such a substance burns. MATERIALS. EXPERIMENT 31 Tests for Organic Compounds Flour, sugar, salt, baking powder, wood, milk, talcum powder, kerosene, gasoline, paraffine, turpentine, olive oil, lard, ether, limewater, alcohol. APPARATUS. rod. Bunsen burner, evaporating dish, test tubes, stirring A. "Charring Test" for an Organic Compound. 1. Heat about 2 grams of flour in an evaporating dish. Note the results. What remains? Heat the black residue strongly. Will it burn? Continue heating till the carbon has entirely disappeared. What is the white ash that remains? Does flour contain organic compounds? Does it contain inorganic compounds? Clean the dish with sapolio. 2. In like manner heat a very small amount of sugar, salt, baking powder, wood, milk, talcum powder. Tabulate your results as follows: ORGANIC COMPOUNDS INORGANIC COMPOUNDS ORGANIC AND INORGANIC |