Difference Between Homogeneous and Heterogeneous Mixtures

Main Difference –  Homogeneous vs Heterogeneous Mixtures

A mixture is a combination of different substances which retain their own characteristics and can be separated by physical means. These dissimilar particles do not undergo any chemical transformation while being a part of the mixture. Mixtures are divided into two major categories known as homogeneous mixtures and heterogeneous mixtures. The terms homo and hetero depict the most prominent difference between homogeneous and heterogeneous mixtures.

The prefix homo refers to the uniformity whereas hetero indicates non-uniformity. Homogeneous mixtures have a uniform composition throughout the system, and heterogeneous mixtures are the opposite. The particles in a heterogeneous are randomly arranged whereas particles in a homogeneous mixture are arranged in a much orderly way, giving rise to a uniform composition.

This article explains,

1. What are Homogeneous Mixtures?
  – Definition, Composition, Characteristics, Examples

2. What are Heterogeneous Mixtures?
  – Definition, Composition, Characteristics, Examples

3. What is the difference between Homogeneous and Heterogeneous Mixtures?

Homogeneous Mixtures – Definition, Composition, Characteristics, Examples

A homogeneous mixture is a mixture with a uniform composition. These mixtures have a uniform composition due to the even distribution of particles. They consist of only one phase. They do not separate into layers, and the constituents are of the molecular or atomic level. Homogeneous mixtures are often called solutions in laymen terms. One of the simplest examples is given below.

Dissolve sugar in water. Take samples from several points of the solution. You will understand that the taste is the same irrespective of the sample point. This indicates that sugar particles are evenly distributed throughout the liquid phase; hence the sugar + water solution is homogeneous.

However, if you keep adding sugar to the solution you might see that there comes a point where sugar would not dissolve anymore. This is called the saturation point. Beyond saturation point, sugar will not dissolve in water anymore, and the homogeneity will be lost. But, if enough solvent is added, the undissolved amount of sugar can be dissolved. This shows that the amount of the substances which takes part in making the mixture should be taken into account in order to maintain the homogeneity of a certain mixture.

The most abundant substance in a homogeneous mixture is called the solvent and the substance which is dissolved in it is called the solute. In the previously discussed example, water is the solvent whereas sugar is the solute which was dissolved.

The composition of a homogeneous mixture (a solution) can be depicted by the term concentration. Concentration is the amount of solute dissolved in the solvent. 

Types and Examples of Homogeneous Mixtures

Liquid mixtures: Pure Water, Vinegar, Coconut oil,

Gas mixtures: Air in the atmosphere

Solid mixtures: Mineral ores, Alloys such as steel, bronze, brass

Heterogeneous Mixtures – Definition, Composition, Characteristics, Examples

Heterogeneous mixtures are made of two or more substances which show distinctive characteristics. These mixtures often tend to separate into phases. The different substances of heterogeneous mixtures are visible to the naked eye. Unlike homogeneous mixtures, heterogeneous mixtures do not have the same composition throughout.

Oil and water is a fine example of a heterogeneous mixture. When oil is mixed with water, the separation of two layers is visible to the eye.  The following picture shows this phenomenon clearly.

Examples of Heterogeneous Mixtures

Emulsions: A heterogeneous mixture of two liquids. The oil and water mixture discussed above is a fine example for this.

Suspension: Large particles of solids are dispersed in a liquid. Soil and water mixture is a suspension

Liquid aerosols: Fine liquid droplets are suspended in a gas. Perfume is a liquid aerosol

Solid aerosol: When solid particles are dispersed in a gas, solid aerosols are created. Smoke is such a solid aerosol.

Difference Between Homogeneous and Heterogeneous Mixtures

Composition

Homogeneous Mixtures: Homogenous mixtures have a uniform composition throughout the mixture.

Heterogeneous Mixtures: Heterogenous mixtures have a mixed composition which may vary from point to point.

Visibility of Components

Homogeneous Mixtures: Components are not visible to the naked eye.

 Heterogeneous Mixtures: Components can be seen easily and distinguished.

Phase Separation

Homogeneous Mixtures: The whole mixture is in the same phase.

Ex: Salty water

 Heterogeneous Mixtures: Substances can be of two phases and layers may separate.

Ex: Oil and water

Particle Source

Homogeneous Mixtures: Particle size is often at atomic or molecular level.

Heterogeneous Mixtures: Heterogenous mixtures have large particle sizes.

Ex: liquid suspensions

Separation of Components

Homogeneous Mixtures: Components cannot be separated easily.

Heterogeneous Mixtures: Components can be separated easily.

Both homogeneous and heterogeneous mixtures are made up of two or more components which are not chemically bonded. These mixtures are used in our day to day life. Maintaining homogeneity is important in producing pharmaceutical drugs, beverages, alloy, plastics etc. Most heterogeneous mixtures are found in nature. Soil and stones are some examples.

Reference:

Job, G.; Ruffler, R. Homogeneous and Heterogeneous Mixtures. Physical Chemistry from a different angle. 2016. 335-355.DOI 10.1007/978-3-319-15666-8_13

Klazema.A.; Heterogeneous Mixture Properties and Examples. Udemy blog. June 16, 2014. Retrieved from https://blog.udemy.com/heterogeneous-mixture/

Ophardt.C.; What are Mixtures and Solutions?. Study of Matter. 2003. Retrieved from http://chemistry.elmhurst.edu/vchembook/106Amixture.html

Image Courtesy:

“101666” (Public Domain) via Pixabay

“Coconut Oil (4404443713)” By Veganbaking.net from USA – Coconut Oil (CC BY-SA 2.0) via Commons Wikimedia

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