Difference Between Methanoic Acid and Ethanoic Acid

Key Difference – Methanoic Acid vs Ethanoic Acid

The key difference between methanoic acid and ethanoic acid is that methanoic acid consists of a hydrogen atom bonded to a carboxylic functional group whereas ethanoic acid consists of a methyl group bonded to a carboxylic acid group.

Carboxylic acid groups have the chemical formula –COOH. There, the carbon atom is bonded to one oxygen atom via a double bond and to a hydroxyl group (-OH) via a single bond. Methanoic acid and ethanoic acid are the simplest forms of carboxylic acids.

CONTENTS

1. Overview and Key Difference
2. What is Methanoic Acid
3. What is Ethanoic Acid
4. Similarities Between Methaic Acid and Ethanoic Acid
5. Side by Side Comparison – Methanoic Acid vs Ethanoic Acid in Tabular Form
6. Summary

What is Methanoic Acid?

Methanoic acid, also known as formic acid, is the simplest carboxylic acid which contains a carboxylic acid group bonded to a hydrogen atom. The general chemical formula of this compound is HCOOH. The molar mass of this compound is 46 g/mol. At room temperature, methanoic acid is a colorless liquid with a pungent odor. The melting point of it is 8.4°C and the boiling point is 100.8°C.

Methanoic acid is miscible with water and polar solvents because it is a polar compound. Also, it is capable of forming hydrogen bonds with water molecules because of the –OH groups present in this molecule. Methanoic acid molecules form dimers (can form two hydrogen bonds between two methanoic acid molecules) in its vapor phase rather than individual molecules.

Figure 01: Methanoic Acid Dimers

There are several common methods of producing methanoic acid;

1. Hydrolysis of methyl formate
2. As a byproduct of the production of other chemicals (ex: acetic acid production)
3. Hydrogenation of CO2 into formic acid

What is Ethanoic Acid?

Ethanoic acid, also known as acetic acid, is the second simplest carboxylic acid that contains a carboxylic acid group bonded to a methyl group. A methyl group has the chemical formula –CH₃. Therefore, the chemical formula of ethanoic acid is CH₃COOH. The molar mass of this compound is 60 g/mol. At room temperature, it is a colorless liquid with a vinegar-like odor. The melting point of ethanoic acid is 16.5°C and the boiling point is 118°C.

Ethanoic acid is a weak acid because it dissociates partially in an aqueous solution. However, concentrated acid is corrosive and can cause skin injuries. The carboxylic acid group of the ethanoic acid can release its proton, which is responsible for the acidic character of this acid. However, it is a monoprotic acid because it can only release one proton per molecule. When a proton is released, the conjugate base of this acid forms called acetate (-COO^–).

Figure 02: Chemical Structure of Ethanoic Acid

Ethanoic acid is mainly produced via methanol carbonylation. In this reaction, methanol and carbon monoxide are reacted with each other in the presence of a catalyst. Another older method of acetic acid production was acetaldehyde oxidation.

What are the Similarities Between Methanoic Acid and Ethanoic Acid?

• Both methanoic acid and ethanoic acid compounds contain carboxylic acid groups.
• Both acids are capable of forming hydrogen bonds.
• Both are colorless liquids at room temperature with a pungent odor.

What is the Difference Between Methanoic Acid and Ethanoic Acid?

Summary – Methanoic Acid vs Ethanoic Acid

Carboxylic acids are organic compounds consist of –COOH groups. Methanoic acid and ethanoic acid are the simplest forms of carboxylic acids. The difference between methanoic acid and ethanoic acid is that methanoic acid consists of a hydrogen atom bonded to a carboxylic functional group whereas ethanoic acid consists of a methyl group bonded to a carboxylic acid group.

Reference:

1. “Formic Acid.” Wikipedia, Wikimedia Foundation, 4 Apr. 2018. Available here
2. “Formic Acid.” National Center for Biotechnology Information. PubChem Compound Database, U.S. National Library of Medicine. Available here
3. “Acetic Acid.” Wikipedia, Wikimedia Foundation, 8 Apr. 2018. Available here

Image Courtesy:

1.’Formic Acid Hydrogenbridge V.1’By Jü – Own work, (CC0) via Commons Wikimedia
2.’1299149′ by OpenClipart-Vectors (Public Domain) via pixabay

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