Problem 82 - A Complete Resource Book in Chemistry for JEE Main

Question

Which compound gives \(\mathrm{CO}_{2}\) with \(\mathrm{NaHCO}_{3} ?\) (a) hexanol (b) phenol + acetic acid (c) n-butanol (d) acetic acid

Step-by-Step Solution

Answer

Acetic acid (option d) gives \(CO_2\) with \(NaHCO_3\).

Step 1: Understanding the Reaction

Sodium bicarbonate (\(NaHCO_3\)) reacts with acids to produce carbon dioxide (\(CO_2\)), water, and a salt. We need to identify which of the given compounds is an acid.

Step 2: Identifying the Compounds

Evaluate each compound: hexanol (an alcohol), phenol + acetic acid (a mixture of a weak acid and an acid), n-butanol (an alcohol), and acetic acid (a carboxylic acid). Among these, acetic acid is known to be a carboxylic acid.

Step 3: Analyzing Acetic Acid and Sodium Bicarbonate Reaction

Acetic acid (\(CH_3COOH\)) reacts with sodium bicarbonate (\(NaHCO_3\)) to produce \(CO_2\), water (\(H_2O\)), and sodium acetate (\(CH_3COONa\)). The chemical equation for the reaction is: \[ CH_3COOH + NaHCO_3 \rightarrow CH_3COONa + CO_2 + H_2O \]

Step 4: Conclusion

Among the given options, only acetic acid reacts with \(NaHCO_3\) to produce \(CO_2\). Therefore, option (d) acetic acid is the compound that gives \(CO_2\) with \(NaHCO_3\).

Key Concepts

Carboxylic Acid

Carboxylic acids are a special group of organic compounds with at least one carboxyl group \((\text{-COOH})\). This group is crucial as it imparts the acidic properties that define these substances. Carboxylic acids are known for their ability to donate a proton \(\text{H}^+\) to other compounds, which is why they are classified as acids. When you mix an acid with a base, like sodium bicarbonate \(\text{NaHCO}_3\), a neutralization reaction occurs. This kind of chemistry is at the heart of why acetic acid reacts effectively with sodium bicarbonate. Compared to other forms of acids, like phenols, carboxylic acids are generally stronger and thus more active in acid-base reactions. This makes them very useful in both industrial applications and daily chemical reactions.

Sodium Bicarbonate Reaction

Sodium bicarbonate \(\text{NaHCO}_3\), often found in household products like baking soda, is a mild base. This means it can react with acids to neutralize them. In the reaction with acetic acid \(\text{CH}_3\text{COOH}\), sodium bicarbonate doesn’t just form harmless salts; it also releases carbon dioxide gas as part of the reaction byproducts.

• Base reacts with acid
• Carbon dioxide gas is produced
• Reaction also produces water and a salt

This process is quite useful in practice; for example, in cooking, where the carbon dioxide gas helps in leavening doughs and batters. The neutralization by sodium bicarbonate and similar bases is a foundational concept in chemistry, illustrating how bases can significantly alter the characteristics of an acidic solution.

Carbon Dioxide Production

Carbon dioxide \(\text{CO}_2\) is a gas that commonly emerges as a product of acid-base reactions. In the case of acetic acid reacting with sodium bicarbonate, the production of carbon dioxide is an indicator of the reaction’s progress.

When you mix baking soda (which contains sodium bicarbonate) with vinegar (acetic acid), the bubbling you observe is due to the rapid release of carbon dioxide gas. This is a common demonstration of a chemical reaction in educational settings. The evolution of carbon dioxide in such reactions not only provides visual evidence of a chemical change but also serves practical applications, such as in baking where it causes doughs to rise.

• Visual indicator of reaction
• Useful in practical applications like baking
• Forms part of everyday chemical reactions

Chemical Equation Analysis

Analyzing chemical equations involves understanding the reactants and products, and balancing the equation so that the number of atoms for each element is equal on both sides. In the acetic acid and sodium bicarbonate reaction, the balanced chemical equation is: \[ \text{CH}_3\text{COOH} + \text{NaHCO}_3 \rightarrow \text{CH}_3\text{COONa} + \text{CO}_2 + \text{H}_2\text{O} \]

This balanced equation shows that one molecule of acetic acid reacts with one molecule of sodium bicarbonate to produce one molecule of carbon dioxide, one molecule of water, and one molecule of sodium acetate. Understanding this helps realize the conservation of mass, a core principle in chemistry that dictates that atoms are neither created nor destroyed in chemical reactions.

• Understand reactants and products
• Balance equations by ensuring equal atoms on both sides
• Demonstrates conservation of mass

Balancing chemical equations is fundamental in chemistry as it ensures that all elements involved in a reaction are accounted for, providing a deeper insight into the processes taking place.