Question

Arrange the following acids in increasing order of their acidic strengths: HCOOH, FCH₂COOH, NO₂CH₂COOH, ClCH₂COOH

• A. HCOOH $<$FCH$_2$COOH$<$ NO$_2$CH$_2$COOH $<$ClCH$_2$COOH
• B. HCOOH $<$ NO$_2$CH$_2$COOH $<$ ClCH$_2$COOH $<$ FCH$_2$COOH
• C. NO$_2$CH$_2$COOH $<$ HCOOH $<$ ClCH$_2$COOH $<$ FCH$_2$COOH
• D. HCOOH $<$ ClCH$_2$COOH $<$ FCH$_2$COOH $<$ NO$_2$CH$_2$COOH

Answer 1

Answer: (D)

HCOOH $<$ ClCH$_2$COOH $<$ FCH$_2$COOH $<$ NO$_2$CH$_2$COOH

Answer 2

Acidic strength depends on the electron-withdrawing ability of substituents attached to the carboxylic acid group. The stronger the electron-withdrawing group, the stronger the acid.The nitro group (NO2) is a stronger electron-withdrawing group than fluorine (F), chlorine (Cl), or hydrogen (H).The correct order is HCOOH $<$ ClCH$_2$COOH $<$ FCH$_2$COOH $<$ NO$_2$CH$_2$COOH