Difference Between Homogeneous and Heterogeneous Reactions

The key difference between homogeneous and heterogeneous reactions is that the reactants and products that take part in homogeneous reactions are in the same phase whereas the reactants and products in heterogeneous reactions are in different phases.

The homogeneity and heterogeneity are two chemical concepts that we describe regarding the uniformity of a subject. The subject can be a mixture of components, reactions, etc. The term homogeneous refers to “same”, and heterogeneous refers to “different”.

CONTENTS

1. Overview and Key Difference
2. What are Homogeneous Reactions
3. What are Heterogeneous Reactions
4. Side by Side Comparison – Homogeneous vs Heterogeneous Reactions in Tabular Form
5. Summary

What are Homogeneous Reactions?

Homogeneous reactions are chemical reactions in which the reactants and products are in the same phase of matter. There are three phases of matter; solid phase, liquid phase and gas phase. If the reactants of a homogeneous reaction are in the gas phase, then the products given by that reaction are also in the gas phase.

The most important homogenous reactions are the reactions between gases and reactions between liquids or substances that are dissolved in liquids.

These reactions are very simple reactions compared to heterogeneous reactions. This is because the chemical changes taking place during these reactions depends only on the nature of the interactions between reactants.

Examples:

• The reaction between carbon monoxide and oxygen in the air
• The reaction between HCl and NaOH in water
• Oxy-acetylene torch burning

What are Heterogeneous Reactions?

Heterogeneous reactions are chemical reactions in which the reactants and products are in two or more phases. Therefore, any of the reactants and products can be in one of the three phases; solid phase, liquid phase or gas phase. Due to this reason, heterogeneous reactions lack the uniformity.

Moreover, the reactions that take place on the surface of a catalyst of a different phase are also heterogeneous. These reactions are more complex because they consider the phase of matter along with the nature of interactions between the reactants.

Examples:

• Coal burning in air
• The reaction between salt and water
• Iron rusting underwater
• The reaction between sodium metal and water

What is the Difference Between Homogeneous and Heterogeneous Reactions?

The homogeneous reactions are chemical reactions in which the reactants and products are in the same phase of matter. Whereas, the heterogeneous reactions are chemical reactions in which the reactants and products are in two or more phases. This is the key difference between homogeneous and heterogeneous reactions. Moreover, homogeneous reactions have uniformity and are very simple. This is because these reactions depend only on the nature of the interactions between reactants. On the other hand, heterogeneous reactions lack uniformity. Also, these reactions are very complex. In addition to that, these reactions consider the phase of matter along with the nature of interactions between reactants. The below infographic presents the difference between homogeneous and heterogeneous reactions in a tabular form.

Summary – Homogeneous vs Heterogeneous Reactions

We can divide the chemical reactions into two types as homogeneous reactions and heterogeneous reactions. The key difference between homogeneous and heterogeneous reactions is that the reactants and products take part in homogeneous reactions are in the same phase whereas the reactants and products in heterogeneous reactions are in different phases.

Reference:

1. “Homogeneity and Heterogeneity.” Wikipedia, Wikimedia Foundation, 28 July 2018. Available here 
2. Britannica, The Editors of Encyclopaedia. “Homogeneous Reaction.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., 21 Dec. 2016. Available here 

Image Courtesy:

1.”1239329″ by Meditations (CC0) via pixabay
2.”SaltInWaterSolutionLiquid” By Chris 73 / Wikimedia Commons, (CC BY-SA 3.0) via Commons Wikimedia