10 PLANT BIOLOGY 



Caution : If in 3 below an explosion occurs, collect another bottle 

 of hydrogen before answering the questions, for an explosion indi- 

 cates that oxygen is mixed with the hydrogen, and such a mixture 

 is dangerous to experiment with. 



1. Examine a bottle of hydrogen, and state whether hydrogen 



is a solid, a liquid, or a gas. Compare its color with 

 that of oxygen and carbon dioxid. 



2. Thrust a lighted stick up into the mouth of an inverted 



bottle of hydrogen. (This experiment will be more 

 satisfactory if the room is darkened.) 



a. State what was done and tell how the hydrogen af- 



fected the burning stick. 



b. How does the burning stick affect the hydrogen ? 



c. What is one difference between oxygen and hydrogen ? 



d. What is one difference between hydrogen and carbon 



dioxid ? 



3. If hydrogen is not being given off from the delivery tube 



in sufficient quantity, pour into the thistle tube 

 some hydrochloric acid. Detach the delivery tube 

 from the rubber tube of the hydrogen apparatus 

 and insert in its place a piece of glass tubing, the 

 upper end of which is drawn out to a small diameter. 

 Collect some of the gas in a test tube by displacement 

 of air and light it. When it burns with only a slight 

 puff, apply a lighted match to the hydrogen escap- 

 ing from the drawn-out tube. 

 Hold over the flame a bottle which is clean and dry. 



a. Describe the preparation of this experiment. 



b. What do you find on the inside of the glass? 



c. What, therefore, is formed when hydrogen burns? 



4. When hydrogen burns, it unites with the oxygen of the 



air and forms oxid of hydrogen, more commonly 

 known as water (formula, H 2 O). 



a. In what respect does hydrogen differ from oxid of 



hydrogen (water) in its most common form? 



b. State how oxid of hydrogen was formed. 



c. In what respects is the method of producing oxid of 



hydrogen (water) the same as that of producing 

 oxide of carbon (carbon dioxid) ? (See 11, 5 above.) 



5. Name five characteristics of hydrogen. 



