An aqueous solution has a normal boiling point of 105.0°C.What is the freezing point of this solution? For water K_b is 0.51°C/m and K_f = 1.86°C/m. A)14.7°C B)-14.7°C C)18.2°C D)-18.2°C

Question

Quizplus · Accepted Answer

The solution has a boiling point elevation of 0°C (105°C - 100°C = 5°C above the normal boiling point of water). Using the formula ΔTf = Kf * m, we can calculate the freezing point depression of the solution:
0°C = 1.86°C/m * m
m = 0°C / 1.86°C/m = 0 mol/kg

This means that the solution does not freeze at all, and therefore the freezing point would be -18.2°C (the freezing point depression of water). However, since the answer choices are given in Celsius rather than Kelvin, we take the absolute value of -18.2°C to get 18.2°C and then give the answer as -18.2°C. So, the correct answer is D.

An Aqueous Solution Has a Normal Boiling Point of 105