Question

Compare acid strength among

1) formic acid, acetic acid, propanoic acid

2)formic acid, acetic acid, benzoic acid

3) chloro, fluoro bromoacetic acids

4) acetic acid, mono,di and trichloro acetic acids

Answer 1

Order of increasing acidic strength:
Stabilisation of the negative charge on anion of acid formed after loss of proton, results in higher acidic strength.
1) Propanoic acid < acetic acid < formic acid
2) Acetic acid < benzoic acid < formic acid
3) Bromoacetic acid < chloroacetic acid < fluoroacetic acid
4) Acetic acid < monochloro acetic acid < dichloro acetic acid < trichloro acetic acid.