Surface Chemistry

The disperse phase in colloidal iron (III) hydroxide and colloidal gold is positively and negatively charged, respectively. Which of the following statements is NOT correct?

  1. Coagulation in both sols can be  brought about by electrophoresis.
  2. Sodium sulphate solution causes coagulation in both sols.
  3. Mixing of the sols has no effect.
  4. Magnesium chloride solution coagulates, the gold sol more readily than the iron (III) hydroxide sol.

Answer

Opposite charges attract each other. Hence on mixing coagulation of two sols may be take place.

The correct option is C.