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प्रश्न
Write a note on Types of emulsion.
उत्तर
There are two types of emulsions:
- Emulsion of oil in water (o/w type):
An emulsion in which the dispersed phase is oil and the dispersion medium is water is called an emulsion of oil in water.
Example:
- Milk consists of particles of fat dispersed in water.
- Other examples include vanishing cream, paint, etc.
- Emulsion of water in oil (w/o type):
An emulsion in which the dispersed phase is water and dispersion medium is the oil is called emulsion of water in oil.
Example:
- Cod liver oil consists of particles of water dispersed in oil.
- Some other examples of this type include butter, cream, etc.
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संबंधित प्रश्न
Define the following with a suitable example, of each:
Gel
Identify the dispersed phase and dispersion medium in the following colloidal dispersions.
- milk
- blood
- printing ink
- fog
Write Hardy-Sulze rules.
What are the applications of Electrophoresis?
What happens when a beam of light is passed through a colloidal sol.
Explain Bredig’s arc method.
Explain the term emulsion and types of emulsions.
Draw labelled diagram Dialysis.
Which type of colloid is formed on the dissolution of soap in water?
Froth and whipped cream are examples of ____________.
Which of the following is multimolecular colloid?
Which of the following statements is CORRECT?
The precipitation power of an electrolyte increases with ______.
Mixing of two oppositely charged sols leads to ____________.
Which of the following can form colloidal sol with water?
Which of the following is multimqlecular colloid?
The movement of colloidal particles towards respective electrode under electric field is called ______.
Pumice stone is an example of ______.
Some colloids are stable by their nature, i.e., gels, alloys, and solid foams. Gelatin and jellies are two common examples of a gel. The solid and liquid phases in a gel are interdispersed with both phases being continuous. In most systems, the major factor influencing the stability is the charge on the colloidal particles. If a particular ion is preferentially adsorbed on the surface of the particles, the particles in suspension will repel each other, thereby preventing the formation of aggregates that are larger than colloidal dimensions. The ion can be either positive or negative depending on the particular colloidal system, i.e., air bubbles accumulate negative ions, sulphur particles have a net negative charge in a sulphur sol, and the particles in a metal hydroxide sol are positively charged. Accumulation of charge on a surface is not an unusual phenomenon-dust is attracted to furniture surfaces by electrostatic forces. When salts are added to lyophobic colloidal systems the colloidal particles begin to form larger aggregates and a sediment forms as they settle. This phenomenon is called flocculation, and the suspension can be referred to as flocculated, or colloidally unstable. If the salt is removed, the suspension can usually be restored to its original state; this process is called deflocculation or peptization. The original and restored colloidal systems are called deflocculated, peptized, or stable sols.
Why does a small amount of salt have such a dramatic effect on the stability of a lyophobic colloidal system? The answer lies in an understanding of the attractive and repulsive forces that exist between colloidal particles. Van der Waals forces are responsible for the attractions, while the repulsive forces are due to the surface charge on the particles. In a stable colloid, the repulsive forces are of greater magnitude than the attractive forces. The magnitude of the electrical repulsion is diminished by addition of ionized salt, which allows the dispersed particles to aggregate and flocculate. River deltas provide an example of this behaviour. A delta is formed at the mouth of a river because the colloidal clay particles are flocculated when the freshwater mixes with the salt water of the ocean.
Gelatin is a _________ colloidal system.
Which of the following process is responsible for the formation of delta at a place where rivers meet the sea?
Which of the following substances will precipitate the negatively charged emulsions?
(i) \[\ce{KCl}\]
(ii) glucose
(iii) urea
(iv) \[\ce{NaCl}\]
What happens when electric field is applied to colloidal solution?
How does the precipitation of colloidal smoke take place in Cottrell precipitator?
Match the items of Column I and Column II.
| Column I | Column II |
| (i) Butter | (a) dispersion of liquid in liquid |
| (ii) Pumice stone | (b) dispersion of solid in liquid |
| (iii) Milk | (c) dispersion of gas in solid |
| (iv) Paints | (d) dispersion of liquid in solid |
Which of the following substances will precipitate the negatively charge emulsion
In which of the following, the Tyndall effect is not observed?
Which of the following electrolytes will be most effective in coagulating negative sol?
Identify the colloidal molecule containing hydrophilic head and hydrophobic tail within it.
