131.Solving a chemistry problem

24 For the coagulation of hydrosol hydrate of iron oxide, 10 ml of sol was added in the first case to 1.15 ml of 1N KC1, in the second - 6.25 ml of 0.01 N Na2S04 and in the third case - 3.7 ml of 0.001 n Na3PO4. Determine the sign of the charge of the sol and calculate the coagulation threshold for each electrolyte.