PRELIMINARY EXPERIMENTS 17 



Conclusion. Describe nitrogen, giving its odor, color, 

 taste, effect on limewater, etc. Does it burn, support 

 combustion, or put out fire ? Is it heavy like carbon dioxide 

 or light like hydrogen? 



Note. The greatest caution should be observed in handling 

 phosphorus, since it ignites spontaneously and its burn is very dan- 

 gerous. 



6. ACIDS, BASES, AND SALTS 



Object. To learn the characteristics of acids, bases, 

 and salts, -and what is meant by neutralization. 



Apparatus. Hydrochloric acid, vinegar, lemon juice, caustic 

 soda, ammonia, limewater, test tubes, evaporating dish, and litmus 

 paper. 



Method. (a) Acids. Put a few drops of hydrochloric 

 acid or vinegar or lemon juice in a test tube and add an inch 

 of water. Examine the mixture to determine the taste, 

 smell, and feeling. Put in a strip of neutral litmus paper or 

 a drop of litmus solution and note the change of color. 



(6) Bases. Add water to a few drops of caustic soda, 

 ammonia, or limewater, as in (a), and examine in the same 

 way. 



(c) Neutralization. To a test tube containing dilute 

 hydrochloric acid add dilute caustic soda drop by drop, and 

 test with litmus until it does not change color. 



If in adding the caustic soda you get too much so that the 

 color becomes blue, reverse the process and add the acid 

 until the solution has no effect on litmus. 



Instead of using litmus paper, a drop of litmus solution 

 may be used to color the acid at the start, then when it 

 becomes lavender, or just between red and blue, the solution 

 will be at the neutral point. 

 EXP. EOT. 2 



