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प्रश्न
Explain micelle formation in a soap solution.
Explain the formation of a micelle in soap solution.
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उत्तर
- A soap molecule has a long hydrophobic hydrocarbon chain called a tail, which is attached to the hydrophilic ionic carboxylate group, called the head.
- In water, the soap molecules arrange themselves to form spherical particles that are called micelles.
- In each micelle, the hydrophobic tails of soap molecules point to the center, and the hydrophilic heads lie on the surface of the sphere.
- As a result of this, soap dispersion in water is stable.
APPEARS IN
संबंधित प्रश्न
Choose the correct option.
The size of colloidal particles lies between ______.
Write a note on Brownian motion.
Write a note on Types of emulsion.
Explain Bredig’s arc method.
Explain the term emulsion and types of emulsions.
Draw labelled diagram of Soap micelle.
Froth and whipped cream are examples of ____________.
Which of the following is multimolecular colloid?
Identify the CORRECT statement.
Which of the following is a heterogeneous mixture?
Which of the following is NOT true for lyophilic colloids?
Mixing of two oppositely charged sols leads to ____________.
Froth is a colloidal solution of ____________.
Pumice stone is an example of ______.
Which of the following ionic species has highest precipitating power?
In which of the following sols there is low affinity between dispersed phase and dispersion medium?
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.
Freshly prepared precipitate sometimes gets converted to colloidal solution by ______.
Which of the following process is responsible for the formation of delta at a place where rivers meet the sea?
An emulsion cannot be broken by:
(i) heating
(ii) adding more amount of dispersion medium
(iii) freezing
(iv) adding emulsifying agent
Which of the following substances will precipitate the negatively charged emulsions?
(i) \[\ce{KCl}\]
(ii) glucose
(iii) urea
(iv) \[\ce{NaCl}\]
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 |
Colloids can
Which of the following substances will precipitate the negatively charge emulsion
Fog is a colloidal solution of ______.
In which of the following, the Tyndall effect is not observed?
Smoke is an example of ______.
Van Arkel's method of purification of metals involves converting the metal to a ______.
Identify the correct decreasing order of precipitation power of flocculating ion added, from following.
