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प्रश्न
Write Hardy-Sulze rules.
Write a note on Hardy–Schulze rule.
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उत्तर
- Generally, the greater the valency of the flocculating ion added, the greater is its power to cause precipitation. This is known as the Hardy–Schulze rule.
- In the coagulation of negative sol, the flocculating power follows the following order:
Al3+ > Ba2+ > Na+ - Similarly, in the coagulation of positive sol, the flocculating power is in the following order:
\[\ce{[Fe(CN)_6]^{4-} > PO_4^{3-} > SO_4^{2-} > Cl^-}\]
संबंधित प्रश्न
Comment on the statement that “colloid is not a substance but a state of substance”.
Define the following with a suitable example, of each:
Multimolecular colloid
Choose the correct option.
The size of colloidal particles lies between ______.
Distinguish between lyophobic and lyophilic sols.
Explain micelle formation in a soap solution.
Froth and whipped cream are examples of ____________.
Which one of the following methods is used to make platinum sol?
Identify the CORRECT statement.
Mist is a colloidal solution of ____________.
Which of the following statements is CORRECT?
Maximum coagulation power is in ____________.
Which of the following is NOT true for lyophilic colloids?
The movement of colloidal particles towards respective electrode under electric field is called ______.
Pumice stone is an example of ______.
Which of the following compounds forms a colloidal solution when dissolved in water?
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.
Colloidal solutions are stable due to ______.
A colloidal system having a solid substance as a dispersed phase and a liquid as a dispersion medium is classified as ______.
Which of the following substances will precipitate the negatively charged emulsions?
(i) \[\ce{KCl}\]
(ii) glucose
(iii) urea
(iv) \[\ce{NaCl}\]
Gelatin which is a peptide is added in icecreams. What can be its role?
What is collodion?
On the basis of Hardy-Schulze rule explain why the coagulating power of phosphate is higher than chloride.
Why is \[\ce{Fe(OH)3}\] colloid positively charged, when prepared by adding \[\ce{FeCl3}\] to hot water?
The coagulation of 200 ML of position sol took place when 0.73 HCL was added to its without changing the volume much. The flocculation value of HCL for the colloid is.
Fog is a colloidal solution of ______.
Smoke is an example of ______.
Identify positively charged sol from following.
