INTRODUCTORY EXERCISES 



23 



into its two parts, hydrogen and oxygen.) Is this exercise 

 synthesis or analysis? 



XI. PROPERTIES OF HYDROGEN (OPTIONAL). 



Apparatus. Granulated zinc or pieces of sheet zinc, dilute sul- 

 phuric acid, 1 bottle with two-holed stopper, thistle tube, glass and 

 rubber connecting tubing, pneumatic trough, large-mouthed bottle, 

 test tubes. 



Directions. Set up the apparatus as in the diagram. 

 Place a handful of zinc in the bottle and pour on enough 

 dilute sulphuric acid through the thistle tube to cover the 

 zinc. (Caution! Keep all 

 flames away from the ap- 

 paratus until the gas is col- 

 lected.) Let this gas escape 

 until it is bubbling freely 

 from the delivery tube ; then 

 collect the large bottle full 

 through water as in Ex. 

 VIII. 2 



A. By the method of Ex. 

 II, 5, take some of the gas 



in a test tube and examine it, holding the test tube mouth 

 downward. Has it any color? odor? taste? 



B. Collect a second test tube full and hold mouth down- 

 ward as before. Tie a match to a wire, light the match, and 

 thrust it up into the tube. Does the match continue to 



1 To dilute sulphuric acid, pour slowly one part of acid into five or six parts 

 of water. Stir while pouring. 



2 The gas will be freer of impurities if passed through a wash bottle con- 

 taining permanganate solution. 



FIG. 10. 



