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Questions and Answers
What is the property of hydrophilic sol colloids under changing conditions?
What is the property of hydrophilic sol colloids under changing conditions?
What is the process of converting a sol to a gel by cooling?
What is the process of converting a sol to a gel by cooling?
What is the state of water in a sol?
What is the state of water in a sol?
What is the Tyndall phenomenon?
What is the Tyndall phenomenon?
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What is the main difference between colloids and true solutions?
What is the main difference between colloids and true solutions?
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What happens when a beam of light is passed through a true solution?
What happens when a beam of light is passed through a true solution?
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What is the basis of the development of the ultra-microscope?
What is the basis of the development of the ultra-microscope?
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What is the term for the conversion of a gel to a sol by heating?
What is the term for the conversion of a gel to a sol by heating?
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What is the state of water in a gel?
What is the state of water in a gel?
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Who discovered the Tyndall phenomenon?
Who discovered the Tyndall phenomenon?
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Study Notes
Types of Colloids
- Whipped cream, soap, and lather are examples of foams, where gas is dispersed in a liquid.
- Pumice stone and rubber are examples of solid foams, where gas is dispersed in a solid.
Classification of Colloids
- Lyophobic colloids have no affinity between dispersed particles and the dispersion medium.
- Lyophilic colloids have a great affinity between dispersed particles and the dispersion medium.
Properties of Colloids
- Particle size: Colloids have particles between 0.1 µ and 0.001 µ in size.
- Visibility of particles: Colloids are invisible to the naked eye, but visible under a powerful microscope.
- Sedimentation of particles: Colloids do not settle down, but may settle under high centrifugation.
- Filtration through filter paper: No residue is formed.
Methods of Formation of Colloids
- Condensation (Association) method: Small particles collect until they reach colloidal size.
- Dispersion (Dissociation) method: Coarse particles are broken down until they reach colloidal size.
Types of Colloids
- 8 types of colloids exist, depending on the state of the dispersed particles and the dispersion medium.
Hydrophilic Sol Colloids
- Hydrophilic sol colloids have the property of setting into a rigid and elastic gel under changing conditions.
Gelation and Solation
- Gelation: The conversion of a sol to a gel by cooling.
- Solation: The conversion of a gel to a sol by heating.
Properties of Sol and Gel
- Sol: Most of the dispersion medium is in the free state, separating the gelatin particles.
- Gel: Much water is present, but is not easily withdrawn, and few molecules of water are free.
Tyndall Phenomenon
- Tyndall phenomenon: Scattering of light by colloidal particles, discovered by John Tyndall.
- The development of the ultra-microscope is based on the scattering of light by colloidal particles.
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Description
This quiz covers the types of colloids, including foams, solid foams, and more, with examples of each. Test your knowledge of dispersed phases and dispersion mediums!
