Question

which of the following is most effective in coagulation of As2S3 sol?

Na3PO4, MgCl2, CaCl2, AlCl3

Answer 1

MgCl2 had for post get km can HCl in the cistern at the others very due a is covalent but

Answer 2

Answer: $AlCl_3$

Explanation: $As_2S_3$ is a negatively charged colloid.

According to Hardy Schulze rule, greater the charge on the oppositely charged ion of the electrolyte added, more effective is the coagulation. Thus to coagulate a negatively charged colloid, we must see the positively charged ions.

$Na_3PO_4$ contains $Na^+$ ions,  $MgCl_2$ contains $Mg^{2+}$ ions,  $CaCl_2$ contains $Ca^{2+}$ ions,  $AlCl_3$ contains $Al^{3+}$ ions.

Thus $Al^{3+}$ bearing the highest positive charge is most effective in bringing the coagulation of negatively charged  $As_2S_3$ colloid.