Question

what is the freezing point of a 0.195m aqueous solution of K2S? (Report amount to three decimal points)

Answer 1

The freezing point depression of water is 1.86°C/m.kg 
K2S dissociates: 
K2S ↔ 2K+ + S 2- 
1mol K2S will produce 3 mol of ions. 
Therefore in the freezing point equation: i = 3 
Depression of freezing point = Kf * i* m 
Depression of freezing point = 1.86*3*0.195 
Depression of freezing point = 1.088°C 
The solution will freeze at - 1.088°C