78 AGRICULTURAL CHEMISTRY 



Experiment //. Neutralization. Repeat Experiment 10, using 

 dilute H 2 SO 4 and NaOH solutions that have been prepared for this 

 experiment. After completing the experiment, clean the burettes 

 thoroughly and return them to the instructor. 



Questions, (i) What was formed when H 2 SO 4 neutralized 

 NaOH? (2) Write the chemical reaction. (3) What was formed 

 as the products of this reaction? (4) How can the salt product be 

 obtained? (5) In writing the reaction, why do we use 2NaOH in- 

 stead of NaOH? (6) How does the product of Experiment 10 

 differ from the product of Experiment n? (7) What other 

 acids could be used for neutralizing NaOH and NH 4 OH ? (8 ) What 

 other bases could be used for neutralizing HC1 and H 2 SO 4 ? 

 (9) What is an acid? (10) What is a base ? (n) What is a salt? 

 (12) Which do we find most abundantly in nature, acids, bases, or 

 salts? Why? 



Experiment 12. Preparation of a salt. Put 10 cc. dilute 

 HC1 and 10 cc. water into the evaporator. Measure out 10 cc. of 

 NaOH into a beaker and add 50 cc. water. Add this diluted NaOH 

 to the evaporator a little at a time until the solution is neutral to 

 litmus paper. Do not dip the paper into the solution, but transfer 

 a drop by means of a glass rod from the evap- 

 orator to the paper. In case too much NaOH 

 has been used, add a drop or two of the acid. 

 Bases or alkalies turn red litmus paper blue, 

 while acids turn blue litmus paper red. When 

 Fig. 39. sodium chiorid the solution is neutral, it has no perceptible 

 crystals (common salt). ac tion upon litmus paper. Place the evap- 

 orating dish upon the sand-bath, and apply heat until the solution 

 is evaporated to dryness. Carefully regulate the flame so as to 

 avoid excessive heating. This will prevent spattering when the 

 solution becomes concentrated. 



Questions, (i) What is left in the evaporator ? (2) From what 

 was it produced? (3) Write the chemical reaction. (4) Taste 

 some of the material in the evaporating dish. How is it possible for 

 this material to be formed from two such unlike compounds as HC1 



