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Surface Chemistry — Chemistry STD 12 Science — Question

Gujarat BoardEnglish MediumSTD 12 ScienceChemistrySurface Chemistry3 Marks
Question
Explain what is observed when:
  1. KCl, an electrolyte, is added to hydrated ferric oxide sol,
  2. An electric current is passed through a colloidal solution,
  3. A beam of light is passed through a colloidal solution.
✓

Answer

  1. Ferric hydroxide sol is positively charged. By adding potassium chloride, the excess chloride ions neutralize its positive charge and cause it to coagulate.
  2. The dispersed phase and dispersion medium migrate towards oppositely charged electrodes (electrophoresis).
  3. The beam of light is scattered by colloidal particles(Tyndall effect).

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