Difference Between Organic Acid and Inorganic Acid

Main Difference – Organic Acid vs Inorganic Acid

In general, acids are chemical compounds that are able to neutralize a base. An acid can form hydronium ions (H3O+) when added to water. Typically, acids are corrosive substances which are liquids at room temperature. Acids can either donate protons (H+) ions to the solution or accept an electron pair from electron rich compounds present in a solution. The main difference between organic acids and inorganic acids is that organic acids are organic compounds having acidic properties and are typically weak acids whereas inorganic acids are inorganic compounds having acidic properties and most of them are strong acids.

Key Areas Covered

1. What is an Organic Acid?
      – Definition, Structure, Properties
2. What is an Inorganic Acid?
      – Definition, Structure, Properties
3. Difference Between Organic Acid and Inorganic Acid
      – Comparison of Key Differences

Key Terms: Acids, Carboxylic Acid, Hydronium Ions, Inorganic Acids, Mineral Acids, Organic Acids, pH Value, Strong Organic Acids, Weak Organic Acids

Difference Between Organic Acid and Inorganic Acid - Comparison Summary

What is an Organic Acid?

Organic acids are organic compounds having acidic properties. Since these are organic compounds, organic acids must have a carbon atom in their structure. The most common type of organic acid is carboxylic acid. The molecular formula of a carboxylic acid can be given as RCOOH. The functional group which causes the acidic property is –COOH. The hydrogen atom in this group can be released as an H+ ion. That is because Oxygen atom is rich with electrons and more electronegative than H atom. Thus, this H atom can be easily separated from –COOH group.

Due to the acidic characteristics, organic acids show a pH value which is less than 7. These acids can turn blue litmus red and are sour in taste. There are two types of organic acids.

  • Strong Organic Acids
  • Weak Organic Acids

Weak acids exist in equilibriums with their conjugate base and H+ ion in a solution whereas strong acids are fully dissociated and do not have equilibriums in an aqueous solution. Most organic acids are weak acids (ex: ethanoic acid) due to their partial dissociation in water. But almost all organic acids are dissolved in organic solvents. The stability of the anion formed after dissociation makes an organic acid a strong acid or a weak acid.

Difference Between Organic Acid and Inorganic Acid

Figure 1: Acetic acid is an organic acid. It is found in vinegar.

What is an Inorganic Acid?

Inorganic acids are inorganic compounds having acidic properties. This means, inorganic acid compounds can donate H+ ions to the aqueous solution or can accept electron pairs from electron rich compounds. Inorganic acids are also called mineral acids. Some inorganic acids have oxygen atoms in their structure whereas some inorganic acids do not. For example, H2SO4 is an inorganic acid having oxygen atoms. But HCN, which is another inorganic acid, does not have oxygen atoms.

Unlike organic acids, inorganic acids do not essentially have a carbon atom in their structure. Some inorganic acids may have carbon atoms while some other inorganic acids may not. For example, HCN has a carbon atom although it is an inorganic acid. HCN is not an organic acid because the only C-H bond it has is easily dissociated into H+ ion and CN ion in water, unlike in organic compounds.

Main Difference - Organic Acid vs Inorganic Acid

Figure 2: The structure of sulfuric acid, an inorganic acid.

Difference Between Organic Acid and Inorganic Acid

Definition

Organic Acids: Organic acids are organic compounds having acidic properties.

Inorganic Acids: Inorganic acids are inorganic compounds having acidic properties.  

Origin

Organic Acids: Most organic acids have a biological origin.

Inorganic Acids: Most inorganic acids have a non-biological origin such as mineral sources.

Solubility in Water

Organic Acids: Organic acids dissolve poorly in water.

Inorganic Acids: Most of the inorganic acids dissolve well in water.

Degree of Acidity

Organic Acids: Organic acids are typically weak acids.

Inorganic Acids: Most inorganic acids are strong acids.

Composition of Atoms

Organic Acids: Organic acids essentially have carbon atoms in their structure.

Inorganic Acids: Inorganic acids may or may not have carbon atoms in their structure.

Conclusion

Both organic acids and inorganic acids show acidic properties such as neutralization of bases, being able to donate protons (H+ ions) or accept electron pairs, turn blue litmus into red, etc. Both substances form hydronium ions (H3O+) in aqueous solutions. The main difference between organic acids and inorganic acids is that organic acids are organic compounds whereas inorganic acids are inorganic compounds.

References:

1.”Organic Acids and Bases.” Chemistry LibreTexts. Libretexts, 14 July 2016. Web. Available here. 14 June 2017. 
2.“Inorganic Acids and Salts.” Inorganic Acids and Salts Products – Alfa Aesar. N.p., n.d. Web. Available here. 14 June 2017. 

Image Courtesy:

1. “Acetic acid atoms” By Vuo at English Wikipedia – Own work (Public Domain) via Commons Wikimedia
2. “Sulfuric-acid-2D” Public Domain) via Commons Wikimedia

 

About the Author: Madhusha

Madhusha is a BSc (Hons) graduate in the field of Biological Sciences and is currently pursuing for her Masters in Industrial and Environmental Chemistry. Her interest areas for writing and research include Biochemistry and Environmental Chemistry.

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