For the coagulation of 100 ml of arsenious sulphide sol, 5 ml of 1 M NaCl is required. What is the flocculation value of NaCl?

Explanation

5 ml of 1 M NaCl contains NaCl
` = 1/1000 xx 5 ` moles = 5 millimoles
Thus, 100 ml of `As_2S_3` sol require NaCl for complete coagulation = 5 millimoles .
`therefore` 1L, i.e., 1000 ml of the sol require NaCl for complete coagulation = 50 millimoles
`therefore ` By definition, flocculation value of NaCl = 50.