For the coagulation of 500 mL of arsenious sulphide sol, 2 mL of 1 M NaCl is required. What is the flocculation value of NaCl?

2 mL of 1 M NaCl contains NaCl=21000=2 m mole Thus 500 mL of As2 S3 sol require NaCl for complete coagulation = 2 m moleHence 1 L, i.e., 1000 mL of the sol require NaCl for complete coagulation = 4 m mole. Therefore, flocculation value of NaCl = 4.