Question

Out of methanoic acid and ethanoic acid which is more acidic and why

Answer 1

An acid is considered stronger if it can lose a hydrogen easily to a base. Out of acetic acid and formic acid, formic acid is considered stronger because the CH3 in acetic acid is electron donating. The CH3 actually contributes electron density towards the O-H bond, making it harder to remove the H, and making acetic acid a weaker acid than formic acid. This is all because the CH3 is an electron donating group.

Another way of explaining this is that the methyl group (-CH3) in acetic acid inductively donates electron density to the COOH, so the O-H bond is less likely to break. Formic acid does not have an electron donating group, so its O-H bond is slightly more polarized and more acidic.