Question

the most acidic and least acidic compounds among the following are respectively
1.ethanoic acid
2.ethanol
3.phenol
4.p-nitrophenol
(A)3 and 2
(B)2 and 1
(C)1 and 2
(D)4 and 3​

Answer 1

Answer:

phenol is most acidic compound

Answer 2

Option (C) is the correct answer

Explanation:

• Ethanoic acid is the most acidic among the following whereas ethanol is the least acidic.
• The acidic compound is the one that has a tendency to produce $H^+$ ions in solution. Phenol and ethanol are considered to be weak acids. But the acidity of phenol is much more than ethanol. This  happens because once a proton is lost, the phenoxide ion undergoes resonance & becomes stable but ethoxide ion does not.
• Also the strength of an acid depends on the stability of its conjugate base. The acetate ion in solution , has 2 resonating structures which provides more stability to it. Phenoxide ion of phenol however negative charge has the lesser electronegative carbon atom. Acetate ion is more stable than phenoxide ion and therefore acetic acid is more stable than phenol.
• Therefore , option (C) is the correct option.