100 AGRICULTURAL CHEMISTRY 



country consumes is a fair index of the extent of its 

 manufacturing industries. 



118. Properties of H 2 SO 4 When pure it is a colorless, 

 heavy, oily liquid. It has a strong affinity for water, 

 with which it combines with evolution of heat. It will 

 decompose organic materials containing C, H, and O, 

 liberating the H 2 O as water, with which it combines, 

 while the carbon, which is partially oxidized, separates 

 and blackens the acid. When sugar is acted upon by 

 concentrated sulfuric acid, this change takes place. 

 H 2 SO 4 is used in the laboratory for drying gases, for 

 drying the air in desiccators, and for oxidizing purposes, 

 as in the determination of organic nitrogen in food mate- 

 rials. It is one of the most useful and extensively used 

 of any of the reagents in the laboratory. 



Experiment 21. Make the following tests with some of the 

 sulfuric acid from the reagent bottles : ( i ) Put 2 or 3 cc. H 2 SO 4 

 into a test-tube ; thrust a splinter of wood into it and leave it there 

 for a few minutes. Then remove the splinter from the test-tube. 

 Wash off the acid and examine the splinter. (2) Place in an 

 evaporating dish 5 cc. water and 15 cc. H 2 SO 4 . Stir it with a small 

 test-tube containing i or 2 cc. NH 4 OH. Observe that the heat 

 generated by the action of the H 2 SO 4 and water, volatilizes some of 

 the NH 3 . (3) Put 10 cc. of water and i cc. of H 2 SO 4 into a test- 

 tube. Then add 2 or 3 cc. of barium chlorid, BaCl 2 . Observe the 

 result. 



Questions, (i) Why is not H 2 SO 4 made from sulfates ? (2) 

 Why is heat produced when water and H 2 SO 4 are mixed? (3) 

 What use was made of this heat in test No. 2? (4) What caused 

 the precipitate when BaCl 2 was added? (5) Write the reaction. 

 (6) What is the name of the product formed? (7) What are some 

 of the uses of H 2 SO 4 ? (8) How many kinds of salts does H 2 SO 4 



