20 mL of 0 . 5 M NaCl is required to coagulate 200 mL of As 2 S 3 solution in 2 hours. The coagulating value of NaCl is ___________.

Step-by-step solution

Coagulating value = Millimoles of electrolyte Volume of sol in litre 20   ml of 0 . 5   M   NaCl contains NaCl = 20 × 0 . 5 = 10   milli   moles 200   ml of As 2 S 3 required NaCl for the coagulation = 10 milli   moles ∴   1000   ml of As 2 S 3 required NaCl for the coagulation = 10 × 1000 / 200 = 50 milli   moles .