OXIDATION PRODUCTS OF ALCOHOLS 51 



EXPERIMENT STUDY XII 



Acetic Acid and Vinegar 



(i) (a) Cool 5 c.c. of 100 per cent acetic acid in running water to at 

 least 15° C. Note crystallization, (b) Dilute the acid with equal 

 volume of water and cool again. (2) Test the dilute acetic acid for 

 color, odor, taste and action toward indicators. (3) To a little sodium 

 carbonate on a watch glass add a few drops of dilute acetic acid. 

 What causes the effervescence? (4) Test acetic acid as in (2) and 

 (3) Exp. XL What does this prove as to ease of oxidation of acetic 

 acid? (5) Examine the following salts of acetic acid as to general 

 character and solubility in water: (a) sodium acetate, (b) lead 

 acetate, (c) copper acetate. (6) Examine pyroligneous acid as to 

 general character. Test acidity by means of litmus paper. (7) Test 

 for acetic acid, or its salts. (See Experiment XV.) (8) Examine 

 cider vinegar as to color, odor, taste, acidity. (9) ..Measure out in 

 a pipette 5.0 c.c. vinegar. Dilute to 50 c.c. Add a few drops of 

 phenolphthalein. Now add from pipette, carefully, with stirring, 

 N/io NaOH until color changes. Calculate acidity of vinegar. 

 I c.c. N/io NaOH is equivalent to .006 g. CH3— COOH. 



POLYCARBOXY ACIDS (POLYBASIC ACIDS) 



Primary alcohols on oxidation yield aldehydes and acids. A 

 dihydroxy alcohol, therefore, should yield a dicarboxy acid, 

 provided both hydroxyl groups are in a ( — CH2OH) grouping 

 for this only yields the carboxyl group on oxidation. These 

 polycarboxy acids possess polyacid properties depending upon 

 the number of carboxyl hydrogens present. They are termed 

 polybasic because they react with more than one molecule of a 

 monoacid base, e.g NaOH. They are analogous to the poly- 

 basic inorganic acids, e.g. sulphuric acid, 



/OH /OH 



H2SO4 or 02S< and phosphoric acid, H3PO4 or OP(-OH 



^OH \0H 



Two dibasic acids are common and more or less widely distrib- 

 uted in nature. 



