The presence of an electron-donating group (EDG), such as an alkyl group, near the -COOH group of a carboxylic acid generally causes the acidic strength to:
A.
Increase, since the electron-donating group stabilizes the carboxylate ion
B.
Remain completely unaffected
C.
Decrease, since the electron-donating group destabilizes the carboxylate ion by intensifying the negative charge
D. Formic acid, because it lacks the electron-donating methyl group present in acetic acid
15.
As the length of the alkyl chain attached to the -COOH group increases (e.g., from acetic acid to propanoic acid to butanoic acid), the acidic strength generally:
A.
Becomes negative (acid becomes a base)
B.
Increases significantly with each additional carbon atom
C.
Decreases slightly, due to the increasing electron-donating inductive effect of the longer alkyl chain
D.
Remains completely unchanged regardless of chain length
C. Decreases slightly, due to the increasing electron-donating inductive effect of the longer alkyl chain
16.
Substitution of a hydrogen atom on the alkyl group of a carboxylic acid with a halogen atom (such as chlorine) generally causes the acidic strength to:
A.
Convert the acid into an alcohol
B.
Increase, since the halogen is an electron-withdrawing group that stabilizes the carboxylate ion
C.
Decrease, since halogens are electron-donating groups
D.
Remain unaffected, since halogens have no electronic effect
A. Chloroacetic acid, due to the electron-withdrawing inductive effect of the chlorine atom
18.
Comparing trichloroacetic acid (Cl₃CCOOH), dichloroacetic acid (Cl₂CHCOOH), and chloroacetic acid (ClCH₂COOH), the order of increasing acidic strength is:
