Join the Most Relevant JEE Main 2025 Test Series & get 99+ percentile! Join Now
Search any question & find its solution
Question: Answered & Verified by Expert
In an experiment, addition of 4.0 mL of 0.005 M $\mathrm{BaCl}_2$ to 16.0 mL of arsenious sulphide sol just causes complete coagulation in 2 h . The flocculating value of the effective ion is
ChemistrySurface ChemistryJIPMERJIPMER 2015
Options:
  • A $\mathrm{Ba}^{2+}, 1.0$
  • B $\mathrm{Ba}^{2+}, 2.0$
  • C $\mathrm{Cl}^{-}, 1.0$
  • D $\mathrm{Cl}^{-}, 2.0$
Solution:
2468 Upvotes Verified Answer
The correct answer is: $\mathrm{Ba}^{2+}, 1.0$
$\mathrm{As}_2 \mathrm{~S}_3$ sol is negatively charged owing to preferential adsorption of $\mathrm{S}^{2-}$ ions. Cation would be effective in causing coagulation.
Flocculating value $=$ minimum millimole of the effective ion per litre of sol
$=\frac{4 \times 0.005}{(4+16) \times 10^{-3}}=1.0$

Looking for more such questions to practice?

Download the MARKS App - The ultimate prep app for IIT JEE & NEET with chapter-wise PYQs, revision notes, formula sheets, custom tests & much more.