36 LABORATORY EXERCISES 



a. Preparation and Properties. Prepare hydrogen in a 

 small, wide-mouth bottle, as shown in Fig. 17. The bottle 

 contains about 5 cu. cm. of granulated zinc and about 10 

 cu. cm. of dilute sulphuric acid. If these substances do not 

 act vigorously, add to them about half a teaspoonful of copper 



sulphate solution. Over the small bottle in- 

 vert a larger bottle (pint fruit jar); the 

 hydrogen displaces the air. A test tube may 

 be used instead of the small bottle. 



After some minutes remove the larger 

 bottle, keeping its mouth downward, and 

 bring to its mouth a long, burning splinter. 

 Does the gas take fire? Where? Push the 

 splinter up into the jar of hydrogen, and 

 hold it steady for a minute or two. Does the 



splinter burn in the hydrogen? Where does it take fire? Why? 

 From the method used in collecting hydrogen do you think 



the gas is heavier, or lighter, than air? 



b. Burning of Hydrogen. Light the hydrogen coming out 

 of the small bottle or test tube. What is the color of its flame? 

 If you cannot see the flame, find out if it is there by holding your 

 hand over it. Invert a cold glass or bottle over the flame. 

 What is deposited? 



Set a tin cup or beaker of cold water over a gas burner. What 

 is deposited on the bottom and sides? Where does it come 

 from? What substance must be present in illuminating gas? 

 Why does the liquid cease to be deposited after a while? 



EXERCISE 35 

 HYDROCHLORIC ACID AND AMMONIA WATER 



Apparatus and Materials. Wide-mouth bottle or drinking glass, 

 glass plate, concentrated hydrochloric acid and ammonia water, red 

 and blue litmus paper, filter paper or blotting paper. 



