Explain what are multimolecular colloids, macromolecular colloids and associated colloids?
Give the difference between them.
Explain what are multimolecular colloids, macromolecular colloids and associated colloids?
Give the difference between them.
-
Multimolecular Colloids: When a large number of atoms or small molecules (having diameters of less than 1nm) of a substance combine together in a dispersion medium to form aggregates having size in the colloidal range, the colloidal solutions thus formed are called multimolecular colloids. The species (atoms or molecules) constituting the dispersed particles in multimolecular colloids are held together by Vander Waals’ forces.
The gold sol, sulphur sol etc. are some examples of multimolecular colloids. A gold sol may contain particles of various size composed of several atoms of gold. Similarly, sulphur sol consists of particles containing about a thousand of S8molecules.
-
Macromolecular Colloids: Certain substances form large molecules whose dimensions are comparable to those of colloidal particles. Such molecules have very high molecular masses and are termed as macromolecules. When such substances are dispersed in suitable dispersion medium, the resulting colloidal solutions are known as macromolecular colloids. Thus, in macromolecular colloids, the dispersed particles are themselves large molecules having very high molecular masses.
Most of the lyophilic sols are macromolecular colloids. For example colloidal dispersion of naturally occurring macromolecules such as starch, proteins, gelatin, cellulose, nucleic acids etc. are macromolecular colloids. Synthetic polymers such as polyethylene, polypropylene, synthetic rubber etc. also form macromolecular colloids when dispersed in suitable solvents.
-
Associated Colloids (Micelles): Associated colloids are those colloids which behave as normal strong electrolytes at low concentrations but exhibit colloidal properties at higher concentrations due to the formation of aggregated particles. The aggregated particles thus formed are called micelles.
Comparisons of multimolecular, macromolecular and associated colloids are as follows:
MULTIMOLECULAR COLLOIDS MACROMOLECULAR COLLOIDS ACCOCIATED COLLOIDS They are formed by the aggregate of a large number of atoms or molecules which generally have diameters less than 1nm, e.g. Sols of gold, sulpher etc. They are molecules of large size e.g. polymers like rubber, nylon, starch. They are formed by of aggregation of a large number of ions in concentrated solution e.g. soap sol. Their molecular masses are not very high. They have high molecular masses. Their molecular masses are generally high. Their atoms or molecules are held together by weak vander Waal’s forces. Due to long chain, the vander Waal’s forces holding them are comparatively stronger. Higher is the concentration; greater are the vander Waal’s forces. They usually have lyophilic character. They usually have lyophobic character. Their molecules contain both lyophobic and lyophilic characters.
-
Multimolecular Colloids: When a large number of atoms or small molecules (having diameters of less than 1nm) of a substance combine together in a dispersion medium to form aggregates having size in the colloidal range, the colloidal solutions thus formed are called multimolecular colloids. The species (atoms or molecules) constituting the dispersed particles in multimolecular colloids are held together by Vander Waals’ forces.
The gold sol, sulphur sol etc. are some examples of multimolecular colloids. A gold sol may contain particles of various size composed of several atoms of gold. Similarly, sulphur sol consists of particles containing about a thousand of S8molecules. -
Macromolecular Colloids: Certain substances form large molecules whose dimensions are comparable to those of colloidal particles. Such molecules have very high molecular masses and are termed as macromolecules. When such substances are dispersed in suitable dispersion medium, the resulting colloidal solutions are known as macromolecular colloids. Thus, in macromolecular colloids, the dispersed particles are themselves large molecules having very high molecular masses.
Most of the lyophilic sols are macromolecular colloids. For example colloidal dispersion of naturally occurring macromolecules such as starch, proteins, gelatin, cellulose, nucleic acids etc. are macromolecular colloids. Synthetic polymers such as polyethylene, polypropylene, synthetic rubber etc. also form macromolecular colloids when dispersed in suitable solvents. -
Associated Colloids (Micelles): Associated colloids are those colloids which behave as normal strong electrolytes at low concentrations but exhibit colloidal properties at higher concentrations due to the formation of aggregated particles. The aggregated particles thus formed are called micelles.
Comparisons of multimolecular, macromolecular and associated colloids are as follows:
| MULTIMOLECULAR COLLOIDS | MACROMOLECULAR COLLOIDS | ACCOCIATED COLLOIDS |
| They are formed by the aggregate of a large number of atoms or molecules which generally have diameters less than 1nm, e.g. Sols of gold, sulpher etc. | They are molecules of large size e.g. polymers like rubber, nylon, starch. | They are formed by of aggregation of a large number of ions in concentrated solution e.g. soap sol. |
| Their molecular masses are not very high. | They have high molecular masses. | Their molecular masses are generally high. |
| Their atoms or molecules are held together by weak vander Waal’s forces. | Due to long chain, the vander Waal’s forces holding them are comparatively stronger. | Higher is the concentration; greater are the vander Waal’s forces. |
| They usually have lyophilic character. | They usually have lyophobic character. | Their molecules contain both lyophobic and lyophilic characters. |
