Problem 45 - 43 Years JEE ADVANCED (1978-2020) + JEE MAIN Chapterwise & Topicwise Solved Papers Chemistry

Question

Formic acid when heated with conc. \(\mathrm{H}_{2} \mathrm{SO}_{4}\) produces

Step-by-Step Solution

Answer

Formic acid forms carbon monoxide when heated with conc. \( \mathrm{H}_{2} \mathrm{SO}_{4} \).

Step 1: Understand the Reaction

Formic acid, with the chemical formula \( \mathrm{HCOOH} \), reacts with concentrated \( \mathrm{H}_{2} \mathrm{SO}_{4} \) (sulfuric acid) under heat. Concentrated sulfuric acid often acts as a dehydrating agent.

Step 2: Identify the Role of Agents

In this reaction, the concentrated sulfuric acid acts as a dehydrating agent, removing a water molecule from formic acid.

Step 3: Write the Chemical Equation

The reaction can be written as: \[ \mathrm{HCOOH} \xrightarrow{\mathrm{conc.} \ \mathrm{H_{2}SO_{4}}} \mathrm{CO} + \mathrm{H_{2}O} \] Formic acid decomposes to produce carbon monoxide (CO) and water (H2O).

Step 4: Verify the Product

The essential product formed when formic acid is dehydrated with concentrated sulfuric acid is carbon monoxide (\( \mathrm{CO} \)). Water is also a byproduct, but the focus is often on the production of \( \mathrm{CO} \).

Key Concepts

Dehydration Reaction

Dehydration reactions are types of chemical reactions where a molecule of water is removed from a compound. In the case of formic acid, when it interacts with concentrated sulfuric acid, the sulfuric acid acts as a dehydrating agent. This means it removes the components of water, specifically one hydrogen atom (H) and one hydroxyl group (OH), from the formic acid molecule, allowing the remainder to form new substances.

These reactions are crucial in organic chemistry as they often serve as a bridge to transform one chemical compound into another by altering its composition.

• Concentrated acids like sulfuric acid are commonly used for dehydration due to their ability to absorb water.
• The dramatic ambient absorption of water by such acids makes them quite effective in driving dehydration reactions.

In essence, dehydration reactions not only transform molecules but also enable the formation of new kinds of chemical bonds. This is highly important for the synthesis of a variety of organic compounds.

Concentrated Sulfuric Acid

Concentrated sulfuric acid is a powerful strong acid with remarkable dehydrating properties. When using concentrated sulfuric acid in chemical reactions, one of its primary roles is to draw out water molecules from other compounds, accelerating reactions like dehydration.

• Its effectiveness is attributed to its high affinity for water, easily pulling the water molecule out of other compounds.
• During the dehydration reaction with formic acid, concentrated sulfuric acid assists in breaking down the formic acid into carbon monoxide and water.

This high capacity for removing water makes sulfuric acid indispensable for various industrial applications, including petroleum refining and production of chemicals. The acidic strength not only enables it to act as a catalyst but also as a direct participant in many chemical transformations.

Carbon Monoxide Production

Carbon monoxide (CO) is a colorless, odorless gas that forms as a product of combustion or decomposition reactions, such as the dehydration of formic acid. During the reaction with concentrated sulfuric acid, formic acid (\( \mathrm{HCOOH} \)) breaks down, resulting in the formation of carbon monoxide and water.

• This specific reaction is notable because it taps into the ability of carbon compounds to transform under heat and acidic conditions.
• The creation of carbon monoxide also highlights the importance of controlling reaction conditions carefully since carbon monoxide, although useful in many industrial processes, is toxic.

In chemistry, capturing and understanding how reactions produce certain gases like CO can offer deeper insights into reaction mechanisms and bond formation. Despite its hazards, carbon monoxide is valuable due to its usefulness in metallurgical processes and the synthesis of organic compounds.