WHAT AIR REALLY IS 



43 



CARBON DIOXIDE 



Materials: Vinegar (or hydrochloric acid). Baking soda (or lime- 

 stone). A glass or beaker. Glass cover. Wood taper. Lime 

 water. Test tubes. 



Method: Pour two tablespocnfuls of vinegar upon a teaspoonful of 

 soda in the glass. Cover immediately. After a minute or two 

 slide the cover to one side and thrust a burning taper into the 

 glass. Produce carbon dioxide in a test tube. Hold the mouth of 

 this tube at an angle over the mouth of a second tube contain- 

 ing some lime water. Carbon dioxide will flow into the lower tube. 



After a minute or two, close the lime water tube with the thumb 

 and shake. This is the lime water test. 



Observation and Conclusion: What characteristic property of carbon 

 dioxide does this show? Result of lime water test? 



NITROGEN 



Materials: Bunsen burner. Test tubes. Rubber stopper. Delivery 

 tube. Shallow dish. Small wide-mouth bottle. Wood taper. 

 Ammonium nitrite. Lime water. 



Method: Heat ten grams of ammonium nitrite in test tube and col- 

 lect Jthe gas by displacement of water as shown in the diagram. 

 When the bottle is full, cover and remove from the water. Open 

 and thrust a burning taper into it. Apply the lime water test. 



Observation and Conclusion: Does nitrogen resemble oxygen or carbon 

 dioxide in its relation to fire? 



