Question

Arrange the following structures in increasing order of acidic behavior in a polar solvent.

a) CH₃OH

b) H₂O

c) HF

d) NH₃

e) HCl

f) CH₃COOH
Option:

1) CH₃OH < NH₃ < H₂O < CH₃COOH < HF < HCl

2) NH₃ < CH₃OH < H₂O < CH₃COOH < HF < HCl

3) CH₃OH < NH₃ < H₂O < HF < CH₃COOH < HCl

4) NH₃ < CH₃OH < H₂O < HF < HCl < CH₃COOH

Answer 1

In increasing order of acidity, the compounds are NH₃ < CH₃OH < H₂O < CH₃COOH < HF < HCl. This is based on the relative electronegativity of the nonmetal atom in each molecule and the stability of the corresponding conjugate base.

Step-by-step explanation:

The question pertains to acidic behavior of a set of compounds in a polar solvent. When comparing the acidity of different substances, one approach is to consider the tendency of a molecule to donate a proton (H+) in solution. For binary hydrogen compounds, acidity generally increases with the electronegativity of the nonmetal atom bonded to hydrogen because the polarity of the bond affects how easily the hydrogen atom can be donated. The original series provided by the student needs correction. The correct order, considering acidity strength, is:

NH₃ < CH₃OH < H₂O < CH₃COOH < HF < HCl

This order is based on the relative electronegativity of the atoms bonded to hydrogen and the ability of the molecule to stabilize the corresponding conjugate base. For instance, HF is more acidic than water because F is more electronegative than O, making the fluoride ion a more stable conjugate base. In contrast, ammonia (NH₃) is less acidic than methanol (CH₃OH) because nitrogen is less electronegative than oxygen and the conjugate base of ammonia, the amide ion (NH₂⁻), is less stable.