Difference Between True Solution and Colloidal Solution

Main Difference – True Solution vs Colloidal Solution

A solution in chemistry is a liquid mixture containing two or more substances. Some solutions are colorless and some are colorful. Some solutions are transparent while other solutions are opaque. Likewise, there are a wide variety of solutions found in our surroundings. Solutions can also be categorized into three major groups based on fundamental differences. These three types include true solutions, colloidal solutions, and suspensions. The main difference between true solution and colloidal solution is that true solutions are homogeneous whereas colloidal solutions are heterogeneous. Homogeneous solutions show a uniform distribution of particles whereas heterogeneous solutions show a non-uniform distribution.

Key Areas Covered

1. What is a True Solution
      – Definition, Properties, Examples
2. What is a Colloidal Solution
      – Definition, Properties, Examples
3. What is the Difference Between True Solution and Colloidal Solution
      – Comparison of key Differences

Key Terms: Colloidal Solutions, Heterogeneous Solutions, Homogeneous Solutions, Opaque, Solution, Transparent, True SolutionsDifference Between True Solution and Colloidal Solution - Comparison Summary

What is a True Solution

A true solution is a mixture of two or more substances. This mixture is in a liquid phase and is transparent. That means the solution allows the light to pass through the solution without scattering light by its particles. Therefore, there are no particles that are visible to naked eye. It has been found that the size of the particles in a true solution is less than 1 nm. Most of the times, these particles are not visible even under powerful microscopes.

The particles of a true solution are not filtered through membrane filters or filter papers. The particles of a true solution do not settle down to the bottom of the container. True solutions are considered as homogeneous. This means that the amount of particles present in a unit volume of the solution is equal everywhere in the solution. Since the size of a particle is very low, the particle density (the amount of particles present in a unit volume) is very high.

Difference Between True Solution and Colloidal Solution

Figure 01: True Solutions are Transparent

A good example for true solutions is an aqueous sugar solution.

  • Sugar in water

Sugar is a solid material. It is well dissolved in water. When sugar is dissolved in water, the mixture of sugar and water is transparent and sugar molecules cannot be obtained by filtration of the solution.

The Brownian effect can be observed in true solutions. Brownian effect is the phenomenon that describes the random motion of particles in a fluid due to their collisions.

What is a Colloidal Solution

A colloidal solution is a heterogeneous mixture of two or more substances. A colloidal solution is also in liquid phase. The particles are invisible to the naked eye. But these particles are visible under powerful microscopes. The size of a particle ranges from 1 nm to 100nm. The mixture is a heterogeneous mixture, i.e., the distribution of particles is not uniform throughout the solution.

Colloidal solutions can be filtered through filter papers with minute holes (such as parchment paper). The particle of colloidal solution does not settle to the bottom of the container under gravity. But the settling can be done by centrifugation, which is a method of obtaining solute particles from a solution as a pellet.

Main Difference - True Solution vs Colloidal Solution

Figure 02: Gelatin Solution is a Colloidal Solution

Colloidal solutions are translucent. That means, a colloidal solution allows light to pass through the solution but the light is scattered by the particles of the solution. Apart from that, Brownian effect can be observed in colloidal solutions. That means, the particles of colloidal solutions are in random motion due to the collisions between them. Gelatin-water mixture is a good example for colloidal solutions.

Difference Between True Solution and Colloidal Solution

Definition

True Solution: A true solution is a homogeneous liquid containing two or more substances.

Colloidal Solution: A colloidal solution is a heterogeneous mixture of two or more substances.

Transparency

True Solution: True solutions are transparent.

Colloidal Solution: Colloidal solutions are translucent.

Particle Size

True Solution: The size of the particles is 1 nm in true solutions.

Colloidal Solution: The size of the particles ranges from 1 nm to 100 nm.

Visibility

True Solution: The particles of true solution are invisible to naked eye and even under powerful microscopes.

Colloidal Solution: The particles of colloidal solution are invisible to naked eye but are visible under powerful microscopes.

Filtration

True Solution: The particles of true solutions cannot be seperated through filtering.

Colloidal Solution: The particles of colloidal solutions can be seperated from filtering through parchment papers.

Settling

True Solution: The particles do not settle at the bottom of the container in true solutions.

Colloidal Solution: The particles of colloidal solutions can settle at the bottom of the container through centrifugation.

Brownian Effect

True Solution: The Brownian effect cannot be observed in true solutions.

Colloidal Solution: The Brownian effect can be observed in colloidal solutions.

Conclusion

Solutions are a very diverse type of matter. They differ from each other due their appearance, nature, composition, etc. However, all solutions are in liquid phase at normal temperature and pressure. True solutions and colloidal solutions are two major types of solutions that are different from each other according to the type and nature of the particles they contain. The main difference between true solution and colloidal solution is that true solutions are homogeneous whereas colloidal solutions are heterogeneous.

References:

1. “Colloidal Solutions, Suspensions And True Solutions.” Colloidal Solutions, Suspensions And True Solutions | TutorsOnNet. N.p., n.d. Web. Available here. 11 July 2017.
2. “Colloidal Solution.” Chemistry Learning. N.p., n.d. Web. Available here. 11 July 2017. 

Image Courtesy:

1. “1886194” (Public Domain) via Pixabay
2. “415425” (CC0) via Max Pixel

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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