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Surface Chemistry — Chemistry STD 12 Science — Question

Gujarat BoardEnglish MediumSTD 12 ScienceChemistrySurface Chemistry3 Marks
Question
  1. What are micelles? How do they differ from ordinary colloidal particles? Give two examples of micelles forming substances.
  2. State Hardy-Schulze rule.
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Answer

  1.  
  1. Substances which behave as normal, strong electrolytes at low concentrations, but exhibit colloidal properties at higher concentrations due to formation of aggregate particles are known as micelles.
Alternate answer
Sr. No. Micelles Ordinary Colloids
$01$ Behave as normal electrolytes at low concentrations and as colloids at high concentration. Concentration does not affect the nature.
$02$ They have lyophobic and lyophilic parts in aggregation. No such polarity is present.
Examples of micelles are: concentrated solution of soap and synthetic detergents.
  1. It states that greater the valency of the active ions, the greater is its precipitating power e.g in the precipitation of –ve sol, $Al^{3+}$ ions are more effective than $Ba^{2+}$ or $Na^+$ ion.

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