How Can Ethanol and Ethanoic Acid Be Differentiated? A Comprehensive Guide for Class 10

The straightforward solution is that ethanol and ethanoic acid can be differentiated by their distinct chemical properties, physical characteristics, and specific chemical tests. Although both are organic compounds, ethanol is an alcohol (CH₃CH₂OH) while ethanoic acid (acetic acid) is a carboxylic acid (CH₃COOH). In this article, we will explore the key differences between these two compounds, explain various simple tests you can perform to distinguish them, and discuss why these differences occur.

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Introduction

In Class 10 science, understanding the differences between various organic compounds is fundamental. Ethanol and ethanoic acid are two commonly studied compounds with distinct functional groups that lead to unique properties. While ethanol is a type of alcohol used widely in beverages, sanitizers, and solvents, ethanoic acid is the main component of vinegar, known for its sour taste and acidic nature. Recognizing the differences between these two substances involves examining their molecular structure, physical properties, and chemical behavior.

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Molecular Structure and Functional Groups

Ethanol (CH₃CH₂OH)

• Functional Group: Hydroxyl group (-OH)
• Structure: Ethanol consists of an ethyl group (CH₃CH₂-) attached to a hydroxyl group. The presence of the -OH group makes ethanol polar and capable of forming hydrogen bonds.
• Properties:
  • Boiling Point: Approximately 78°C.
  • Solubility: Completely miscible in water.
  • Odor: Characteristic alcoholic odor.

Ethanoic Acid (CH₃COOH)

• Functional Group: Carboxyl group (-COOH)
• Structure: Ethanoic acid contains a methyl group (CH₃-) attached to a carboxyl group. The carboxyl group is responsible for its acidic properties.
• Properties:
  • Boiling Point: Approximately 118°C (often decomposes before boiling in pure form).
  • Solubility: Soluble in water; forms hydrogen bonds.
  • Odor and Taste: Pungent, sour smell and taste, characteristic of vinegar.

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Physical Property Differences

Odor and Taste

• Ethanol:
  • Has a distinct, mild alcoholic odor.
  • In small quantities, it may taste slightly sweet.
• Ethanoic Acid:
  • Possesses a sharp, pungent odor.
  • Has a sour taste, which is why vinegar (diluted ethanoic acid) is sour.

Boiling and Melting Points

• Ethanol:
  • Boiling point is lower (around 78°C), indicating weaker intermolecular forces compared to ethanoic acid.
• Ethanoic Acid:
  • Boiling point is higher (around 118°C) due to stronger hydrogen bonding from the carboxyl group.

Solubility

• Both ethanol and ethanoic acid are soluble in water due to their ability to form hydrogen bonds, but their solubility characteristics may differ slightly in non-polar solvents.

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Chemical Tests to Differentiate Ethanol and Ethanoic Acid

To distinguish between ethanol and ethanoic acid in a laboratory or classroom setting, several simple chemical tests can be performed:

1. Litmus Test

• Ethanol:
  • Being neutral, ethanol does not change the color of litmus paper.
• Ethanoic Acid:
  • As a weak acid, ethanoic acid will turn blue litmus paper red.

2. Reaction with Sodium Bicarbonate (NaHCO₃)

• Ethanol:
  • Does not react with sodium bicarbonate.
• Ethanoic Acid:
  • Reacts with sodium bicarbonate to produce carbon dioxide gas, water, and sodium ethanoate:

    \text{CH}_3\text{COOH} + \text{NaHCO}_3 \rightarrow \text{CH}_3\text{COONa} + \text{CO}_2 \uparrow + \text{H}_2\text{O}

3. Reaction with Calcium Carbonate (CaCO₃)

• Ethanol:
  • No reaction occurs.
• Ethanoic Acid:
  • Reacts with calcium carbonate to produce calcium ethanoate, carbon dioxide, and water:

    2\,\text{CH}_3\text{COOH} + \text{CaCO}_3 \rightarrow \text{Ca(CH}_3\text{COO)}_2 + \text{CO}_2 \uparrow + \text{H}_2\text{O}

4. Infrared (IR) Spectroscopy (Advanced Technique)

• Ethanol:
  • Displays a broad O–H stretching peak around 3200–3600 cm⁻¹.
• Ethanoic Acid:
  • Shows a very broad and intense O–H stretching peak due to hydrogen bonding in the carboxyl group, along with a strong C=O stretching peak near 1700 cm⁻¹.
• Note:
  • While IR spectroscopy is more advanced, it provides clear evidence of the different functional groups present in each compound.

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Practical Considerations in a Classroom Setting

For Class 10 students, these tests are often simplified and demonstrated in the lab:

• Safety Precautions:
  Always wear appropriate safety gear, such as gloves and goggles, when handling chemicals.
• Observation Skills:
  Note the changes in litmus paper, observe any bubbling or effervescence, and record your observations accurately.
• Understanding Results:
  Discuss how the reactions (or lack thereof) correlate with the molecular structures of ethanol and ethanoic acid. This reinforces the connection between theory and experimental observations.

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Conclusion

In conclusion, ethanol and ethanoic acid can be differentiated based on their physical properties and chemical behavior. Ethanol, an alcohol, is neutral in pH, has a lower boiling point, and does not react with sodium bicarbonate, whereas ethanoic acid, a carboxylic acid, is acidic—turning blue litmus red—and reacts with sodium bicarbonate to produce carbon dioxide. These tests, along with differences in odor, taste, and spectroscopic signatures, provide reliable methods for distinguishing between the two compounds.

Understanding these differences not only helps in academic learning but also builds a solid foundation for more advanced studies in chemistry. By linking theoretical knowledge with practical experiments, students can gain a deeper insight into the behavior of chemical substances.

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Disclaimer: This article is intended for informational and educational purposes only. The experiments and tests described should be performed under proper supervision and with appropriate safety measures. Always consult your teacher or laboratory supervisor for guidance before conducting any chemical tests.

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