Activity 16: Structural effects on Acidity and basicity

Question 1

Which is more acidic? Phenol or Ethanol. why?

Answer 1

Phenol. due to resonance effect. Phenol is more acidic because the conjugate base is stabilized by pi electron stabilization.

Question 2

Give the trend in increasing acidity of the 3 compounds. ( acetic acid, monochloroacetic acid, trichloroacetic acid)

Answer 2

acetic acid < monochloroacetic acid < trichloroacetic acid

Question 3

Which is more basic, aniline or diethylamine?

Answer 3

Diethylamine. due to electron-repelling inductive effect, causing the lone pair readily available and thus increasing the electron density on the Nitrogen atom and making it a stronger base

Question 4

Reaction w/ silver ammonium chloride:

Acetylene

Answer 4

forms gray/white precipitate

Question 5

Reaction w/ silver ammonium chloride:

benzene
heptane

Answer 5

both have no reaction thus forming no precipitate

Question 6

Predict the trend in increasing acidity of acetylene, benzene, and n-heptane

Answer 6

n-heptane < benzene < acetylene

Question 7

Explain the trend (acetylene, benzene, n-heptane) in terms of pertinent structural effects

Answer 7

Acetylene is is the most acidic due to its triple bond followed by benzene due its double bond and the n-heptane due to its single bond. Note that the higher the s-character in a bond, the more acidic it becomes.