CHAPTER XI 

 Hydrochloric Acid, Chlorin, and Chlorids 



85. Occurrence. The element chlorin is never found 

 in a free state in nature, but is always in combination 

 with other elements, as with sodium, forming sodium 

 chlorid. With hydrogen, chlorin forms hydrochloric 

 acid. 



86. Preparation. Hydrochloric acid is produced by 

 the action of H 2 SO 4 on NaCl, the reaction being 

 2 NaCl + H 2 SO, = Na 2 SO< + 2HC1. Heat is applied 

 and the hydrochloric acid gas is expelled and col- 

 lected in water. In the preparation of hydrochloric acid, 

 the Cl part of the compound is supplied by the NaCl, while 

 the sulfuric acid furnishes the hydrogen. Hydrochloric 

 acid can also be made by direct union of the elements 

 hydrogen and chlorin. It is prepared in the laboratory 

 in the following way : 



Experiment 13. Preparation of hydrochloric acid. Arrange 

 the apparatus as shown in Fig. 40. A sand-bath, containing 

 sand, is placed upon either the tripod or the large ring of the iron 

 ring-stand. Tube B connects flask A with Woulff bottle C, which 

 contains 100 cc. of water. The tube is made from a piece of glass 

 tubing 22 to 24 inches long, with one right-angled bend about 3 

 inches from the end, and another, parallel and about 6 inches from 

 the first bend. This tube is connected with both flask A and the 

 Woulff bottle by means of tight-fitting corks. Tube B passes into 

 the bottle but not below the surface of the liquid. Through a tight- 

 fitting cork in the middle neck of Woulff bottle C passes a safety 

 tube so adjusted that it dips just below the surface of the water in 

 C. This safety-tube is a straight piece of glass tubing, 9 or 10 



