1. Experiment 15
Reactions of Carboxylic Acids

2. Pre-laboratory Questions:

3. DRAW THE STRUCTURAL FORMULA
OF THE FOLLOWING COMPOUNDS:
Acetic acid, monochloroacetic acid, trichloroacetic
acid, benzoic acid, oxalic acid, succinic acid, lactic
acid, tartaric acid, citric acid and propionic acid.

4. Acetic acid

5. Monochloroacetic acid

6. Trichloroacetic acid

7. Benzoic acid

8. Oxalic acid

9. Succinic acid

10. Lactic acid

11. Tartaric acid

12. Citric acid

13. Propionic acid

14. WRITE THE EQUATION THAT SHOWS
THE IONIZATION OF VALERIC ACID IN
WATER.

15. +
+HO
2 H3O +

16. WRITE EQUATIONS SHOWING THE
REACTIONS OF VALERIC ACID WITH
NAOH AND NAHCO3.

17. + NaOH
+ NaHCO
3 + CO2 + H2O

18. RESULTS & DISCUSSIONS
A. ACIDITY AND STRUCTURE
Acetic acid Monochloroacetic Trichloroacetic
acid acid
pH 3.0 2.0 1.0

19. DISCUSSION:
Trichloroacetic acid is more acidic because of
the presence of the 3 chlorine atoms which
tend to pull the electrons closer leaving the
Hydrogen more prone to leave

20. B. SOLUBILITY
Water NaHCO3
Acetic Acid - 0.5 mL
Benzoic Acid Did not dissolve 0.5 mL
Oxalic Acid 0.5 mL 0.5 mL
Lactic Acid 0.5 mL 1 mL

21. EFFECT OF OXIDIZING AGENTS
KMnO4 Tollens’ Reagent
Formic acid Purple to green (w/o heating) Silver mirror formed
Green to brown (after heating)
Acetic acid No change in color No silver mirror formed
Lactic acid Purple to green (w/o heating) No silver mirror formed
Green to brown (after heating)
Tartaric acid Purple to bloody red (w/o heating) No silver mirror formed
Bloody red to clear sol’n (after
heating)
Citric acid Purple to clear sol’n No silver mirror formed
Oxalic acid No change in color No silver mirror formed
Benzoic acid No change in color No silver mirror formed
Propionic acid Purple to reddish brown (after White precipitate
heating)
Water No change in color No silver mirror formed

22. FORMIC PROPIONIC TARTARIC CITRIC ACETIC

23. OXALIC LACTIC BENZOIC

24. DISCUSSION for KMnO4
•Carboxylic acids are relatively resistant to oxidation.
However, some acids, like alpha-hydroxy acids may be
oxidized.
Acetic acid Lactic acid

25. DISCUSSION for Tollen’s Reagent
• Mild oxidizing agents like Tollen’s reagent are
easily reduced by aldehydes to silver mirror.
Formic acid O
C
H OH

26. ESTERIFICATION
• Smells like Guava ;
• Did not dissolve in water
DISCUSSION:
There are two evidences of esterification reactions:
1. The change in solubility – the product ester is not water
soluble, so two layers were formed
2. A distinctive change in odor – they are usually sharp and
extremely pleasant

27. CARBOXYLIC ACID AND ITS SALTS
Cold water: salicylic acid did not dissolve
Hot water: salicylic acid dissolved
When cooled to room temperature: crystals were formed
Addition of 3M NaOH in erlenmeyer flask: crystals were dissolved
Addition of 3M HCl in erlenmeyer flask: crystals were reformed

28. QUESTIONS

29. 1. What is the effect of Cl on the
acidity of carboxylic acids?
Cl is electronegative which tends to pulls
electrons closer to them leaving the hydrogen
more readily to leave making it highly acidic

30. 2. Explain the effect of
the structure of the
samples used on
solubility behavior.

31. Acetic acid

32. Monochloroacetic acid

33. Trichloroacetic acid

34. Benzoic acid

35. Oxalic acid

36. Succinic acid

37. Lactic acid

38. Tartaric acid

39. Citric acid

40. Propionic acid

41. 3. Write the equation
showing the ester
formation.

42. Conclusion
• In conclusion, the structure of the compounds
plays an important role in its solubility.
• Electronegativity plays a big role on the
carboxylic acid’s acidity.
• Carboxylic acids are usually resistant to
oxidization but there are some cases that they
can be oxidized.