Question

Under the influence of an electric field, the particles in a sol migrate towards the cathode. The coagulation of the same sol is studied using $NaCl,N{a}_{2}S{O}_4$ and $N{a}_{3}P{O}_4$ solutions. The coagulating values will be highest for:

• A. $NaCl$
• B. $N{a}_{2}S{O}_4$
• C. $N{a}_{3}P{O}_4$
• D. Same for all

Answer 1

The correct option is A $NaCl$

The sol particles migrate towards the cathode which is negatively charged, so they must be positively charged. Hence, adding anions would help in coagulation. Greater the valency of anions, lower will be its coagulating value.