Paper: CSIR-NET December 2011 · Subject: Physical Chemistry · Chapter: Surface Chemistry · Topic: Surface Chemistry – General · Marks: 2 · Difficulty: Medium
Flocculation value of $\mathrm{K_2SO_4}$ is much less than that of KBr for Sol A. Floccultion value of $\mathrm{CaCl_2}$ is much less than that of NaCl for Sol B. Which of the following statements is correct?
(a)Sol A is negatively charged and Sol B is positively charged
(b)Both the sols are negatively charged.
(c)Sol A is positively charged and sol B is negatively charged
(d)Both the sols are positively charged.
Answer
Answer: C ✓ checked by 4AB · confidence high
Explanation
Hardy–Schulze: SO₄²⁻ coagulates sol A far better than Br⁻, so A is positive; Ca²⁺ coagulates sol B better than Na⁺, so B is negative (c).