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Surface Chemistry — Chemistry STD 12 Science — Question

Gujarat BoardEnglish MediumSTD 12 ScienceChemistrySurface Chemistry5 Marks
Question
Match the items given in Column $I$ and Column $II.$
  Column $I$   Column $II$
$(i)$ Protective colloid. $(a)$ $FeCl_3 + NaOH.$
$(ii)$ Liquid - liquid colloid. $(b)$ Lyophilic colloids.
$(iii)$ Positively charged colloid. $(c)$ Emulsion.
$(iv)$ Negatively charged colloid. $(d)$ $FeCl_3 +$ hot water.
✓

Answer

  Column $I$   Column $II$
$(i)$ Protective colloid. $(b)$ Lyophilic colloids.
$(ii)$ Liquid - liquid colloid. $(c)$ Emulsion.
$(iii)$ Positively charged colloid. $(d)$ $FeCl_3 +$ hot water.
$(iv)$ Negatively charged colloid. $(a)$ $FeCl_3 + NaOH.$
Explanation:
  1. Lyophilic colloids have a unique property of protecting lyophobic colloids. When a lyophilic sol is added to the lyophobic sol, the lyophilic particles form a layer around lyophobic particles and thus protect colloid.
  2. If a mixture of two immiscible or partially miscible liquids is shaken, a coarse dispersion of one liquid in the other is obtained which is called emulsion.
  3. If $FeCl_3$ is added to excess of hot water, a positively charged sol of hydrated ferric oxide is formed due to adsorption of $Fe^{3+}$ ions.
  4. When ferric chloride is added to $NaOH$ a negatively charged sol is obtained with adsorption of $OH^-$ ions.

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