For the coagulation of 100 ml of arsenious sulphide solution, 5ml of 1M NaCl is required. Calculated the flocculation value .

Explanation

Number of millimolels of electrolyte NaCl required to coagulate 100ml of sol `= 1 xx 5 = 5`
Numbre of millimoles of electrolyte required to coagulate 1000 ml of sol = `5 xx 1000/100 = 50`
The minimum number of moles of electrolyte per litre required to cause precipitation is called flocculation value. Flocculating value of NaCl is 50 millimole `L^(-1)`.