EXERCISE 30 A 



CAN WATER BE FORMED BY BURNING HYDROGEN IN OXYGEN? 



Materials. Apparatus used in Exercise 29, also that used in Exercise 30 ; clean, dry bottle ; a 

 short glass tube drawn to a small opening. 



Directions. This exercise should be performed by the teacher. 



Fill a clean dry bottle with oxygen (see figure). Now gener- 

 ate hydrogen with the apparatus used in Exercise 30. Insert a 

 small glass tube drawn to a rather small opening into the rubber 

 delivery tube. After the hydrogen has been forming for a few 

 minutes, catch a test tube of the gas by holding the tube in an 

 inverted position and bringing the delivery tube into the mouth 

 of the test tube. Remove the test tube from the delivery tube, 

 and holding it with the mouth downward, bring a lighted match 

 to the mouth of the tube. If an explosion occurs, catch another 

 tube of the gas and test. When the gas is free from air and burns 

 with a noiseless flame, light the gas issuing from the tip of the delivery tube and lower the hydrogen 

 flame into the clean bottle. A cover for the bottle may be made by thrusting the glass tube through 

 a piece of cardboard. Allow the hydrogen to burn until it is extinguished. What does the deposit 

 on the inside of the bottle appear to be ? 



Additional problems. What does this exercise prove about the composition of water ? 

 How do you explain the formation of water when a candle burns ? 



