Difference Between Multimolecular and Macromolecular Colloids

Main Difference – Multimolecular vs Macromolecular Colloids

Colloids are a type of homogeneous mixture in which the dispersed particles do not settle out. Colloids can be divided into groups depending on several parameters such as the type of particles present in the colloid, physical state of particles in the colloid, nature of the interaction between particles and the dispersion medium, etc. When colloids are categorized based on the type of particles present in the colloid, there are three types of colloids as multimolecular colloids, macromolecular colloids, and micelles. The main difference between multimolecular colloids and macromolecular colloids is that multimolecular colloids have molecules with low molecular weights whereas macromolecular colloids have molecules with high molecular weights.

Key Areas Covered

1. What are Multimolecular Colloids
      – Definition, General Properties, Examples
2. What are Macromolecular Colloids
      – Definition, General Properties, Examples
3. What is the Difference Between Multimolecular and Macromolecular Colloids
      – Comparison of Key Differences

Key Terms: Colloids, Lyophilic, Lyophobic, Macromolecular Colloids, Molecular Weight, Multimolecular Colloids

What are Multimolecular Colloids

Multimolecular colloids are particles formed by the aggregation of smaller molecules when they are dissolved in a solvent. These small molecules should have a diameter less than 1 nm in order to form particles in colloidal range (around 100 nm). Therefore, the molecules that form multimolecular colloids are low molecular weight compounds.

In these multimolecular colloids, the small molecules (or atoms) are held together by Van der Waal forces. Usually, these colloids have a lyophobic nature. This means these colloids have less or no attraction forces with the dispersion medium.

Figure 1: Ferric Hydroxide is an example multimolecular colloids

Examples of multimolecular colloids include sulfur sol (composed of a large number of S₈ molecules), hydroxides such as Ferric hydroxide, gold sol (composed of a large number of gold atoms), etc.

What are Macromolecular Colloids

Macromolecular colloids are individual particles that are large enough to be considered as colloids (diameter around 100 nm). These particles are molecules with high molecular weights. They are also called macromolecules due to their high molecular weight and the large dimensions.

When these compounds are added to a solvent, the resulting solution has these individual particles dispersed all over the solution. This solution is known as a macromolecular colloid. Most of the lyophilic colloids fall into this category of colloids. Lyophilic colloids are solvent loving particles that can have strong interactions between the particles and the dispersion medium.

Figure 01: Cornstarch is an example of a macromolecular colloid

Some examples of macromolecular colloids include starch, proteins, cellulose, some synthetic polymers such as polyethylene, etc. 

Difference Between Multimolecular and Macromolecular Colloids

Definition

Multimolecular Colloids: Multimolecular colloids are particles formed by the aggregation of smaller molecules when they are dissolved in a solvent.

Macromolecular Colloids: Macromolecular colloids are individual particles that are large enough to be considered as colloids.

Dimensions

Multimolecular Colloids: Multimolecular colloids are formed from particles having diameters less than 1 nm.

Macromolecular Colloids: Macromolecular colloids are formed from particles having diameters in the colloidal range (around 100 nm).

Molecular weight

Multimolecular Colloids: Multimolecular colloids are formed from particles having low molecular weights.

Macromolecular Colloids: Macromolecular colloids are formed from particles having high molecular weights.

Formation

Multimolecular Colloids: In the formation of multimolecular colloids, when the compound is added to a dispersion medium, small molecules form aggregates having dimensions in the colloidal range.

Macromolecular Colloids: In the formation of macromolecular colloids, when the compound is added to a dispersion medium, compound separates into individual molecules which have their dimensions in colloidal range.

Nature

Multimolecular Colloids: Multimolecular colloids have a lyophobic nature.

Macromolecular Colloids: Macromolecular colloids have a lyophilic nature.

Forces

Multimolecular Colloids: The aggregates in multimolecular colloids are held together via weak Van der Waal forces.

Macromolecular Colloids: There are strong attraction forces between particles and the liquid in macromolecular colloids.

Conclusion

Multimolecular colloids and macromolecular colloids are two types of colloids that can be categorized depending on the type of particles that are present in the colloidal solution. The main difference between multimolecular colloids and macromolecular colloids is that multimolecular colloids have molecules with low molecular weights whereas the molecules in macromolecular colloids have high molecular weights.

References:

1. “Classification of Colloids.” Classification Of Colloids Based On Physical State – Study Material for IIT JEE | askIITians, Available here.
2. “Classification of Colloids | Dispersed Phase & Dispersion Medium | Chemistry | Byju’s.” Chemistry, Byjus Classes, 27 Oct. 2017, Available here.
3. “Organic Chemistry | What is the difference between multimolecula-AskIITians.” Askiitians Discussion Board, Available here.

Image Courtesy:

1. “Fe(OH)3” By Leiem – Own work (CC BY-SA 4.0) via Commons Wikimedia
2. “Cornstarch and water mixture” By Baminnick – Own work (CC BY-SA 3.0) via Commons Wikimedia