Q.Differentiate between methanoic acid and ethanoic acid.

HCOOH is stronger and reducing (has an -CHO group); CH3COOH is weaker and non-reducing because of the +I effect of CH3.

Methanoic (formic) acid, HCOOH, and ethanoic (acetic) acid, CH3COOH, differ as follows:

1. Structure:

• Methanoic acid: H-COOH (one carbon; the carboxyl carbon also bears an H, so it contains a hidden -CHO group).

• Ethanoic acid: CH3-COOH (two carbons; carboxyl attached to methyl).

2. Acidic strength:

• Methanoic acid is a stronger acid (Ka ~ 1.8 x 10^-4).

• Ethanoic acid is weaker (Ka ~ 1.8 x 10^-5), because the electron-releasing +I effect of the CH3 group destabilises the acetate ion.

3. Reducing property:

• Methanoic acid acts as a reducing agent — it reduces Tollens' reagent (gives silver mirror) and Fehling's solution (red ppt) because of the -CHO grouping. …