HYDROCHLORIC ACID, CHLORIN, AND CHLORIDS 8 1 



inches long. Woulff bottle C is connected with a second Woulff 

 bottle by means of a bent tube which passes below the water in the 

 second bottle but is above 

 the water in the first bot- 

 tle. The apparatus, as 

 constructed, allows the 

 gas which is generated in 

 flask A to pass through 

 into C and saturate the 

 water. Some of the acid 

 passes over into the sec- 

 ond Woulff bottle. Since 

 the delivery tubes in C do 

 not pass below the surface 

 of the liquid, and the 

 pressure is equalized, no 

 liquid can be drawn back 

 into flask A. 



Place 15 grams sodium 

 chlorid (NaCl, common 

 salt) and 30 cc. of concen- 

 trated H 2 SO 4 in flask A. 

 Apply heat to the flask, 

 and after ten minutes re- 

 move the burner and test Fig. 40. Preparation of hydrochloric acid, 

 the liquid in both Woulff bottles with litmus paper. Then make 

 the following tests : 



( i ) Disconnect the delivery tube and test the escaping gas with 

 wet litmus paper. (2) Collect a little of the gas in a test-tube, and 

 test it with a burning splinter. (3) Put 2 or 3 cc. of silver nitrate 

 (AgNO 3 ) into a test-tube and then a like amount of HC1 from the 

 first Woulff bottle. Observe the result. (4) Leave the test-tube and 

 contents exposed to strong sunlight for a few minutes. (5) Put a 

 small piece of zinc into a test-tube and cover it with some of the 

 acid from the first Woulff bottle. Observe the result. 



Questions. ( i ) What chemical reaction took place when H 2 SO 4 



6 



