Question

What is the freezing point (in °C) of a 0.195 m aqueous solution of K2S? Enter your rounded answer with 3 decimal places. (Kf for water = 1.86 °C/m) a) -1.734°C

b) -2.457°C
c) -3.589°C
d) -0.935°C

Answer 1

To find the freezing point of a solution, we can use the formula ΔTf = Kf * m, where ΔTf is the freezing point depression, Kf is the molal freezing point depression constant, and m is the molality of the solution. Given that the molality of the solution is 0.195 m and Kf for water is 1.86°C/m, the freezing point is calculated to be 0.3627°C. Therefore, none of the given options (a, b, c, d) are correct.

Step-by-step explanation:

To find the freezing point of the solution, we can use the formula ΔTf = Kf * m, where ΔTf is the freezing point depression, Kf is the molal freezing point depression constant, and m is the molality of the solution.

Given that the molality of the solution is 0.195 m and Kf for water is 1.86°C/m, we can substitute these values into the formula to calculate the freezing point depression:

ΔTf = 1.86°C/m * 0.195 m = -0.3627°C

The freezing point of the solution is the same as the freezing point depression, but with opposite sign:

Freezing point = -ΔTf = -(-0.3627°C) = 0.3627°C

Since we are asked for the freezing point in °C, our rounded answer is 0.363°C. Therefore, none of the given options (a, b, c, d) are correct.