Question

Which of the following is obtained when formic acid is heated with conc. H$_2$SO$_4$?

• A. CO$_2$
• B. CH$_3$HSO$_4$
• C. Oxalic acid
• D. CO

Hint:

Formic acid is unique among carboxylic acids because it readily decomposes to CO in presence of conc. H$_2$SO$_4$.

Answer 1

The Correct Option is D

Step 1: Reaction principle.
Formic acid (HCOOH) on dehydration with concentrated sulfuric acid undergoes elimination of water to form carbon monoxide (CO).
Step 2: Reaction.
\[ HCOOH \xrightarrow{conc.\ H_2SO_4,\ \Delta} CO + H_2O \] Step 3: Analysis of options.
(A) CO$_2$: Produced when formic acid is heated alone, not with conc. H$_2$SO$_4$.
(B) CH$_3$HSO$_4$: Not formed in this reaction.
(C) Oxalic acid: Not formed here.
(D) CO: Correct, dehydration product.
Step 4: Conclusion.
The correct answer is (D) CO.