Calculate the freezing point of a solution containing 5.0 grams of KCl and 550.0 grams of water. The molal freezing point depression constant (K_f)for water is 1.86 °C m^-1. A)-0.45 °C B)+0.45 °C C)-0.23 °C D)+0.23 °C E)1.23 °C

Question

Quizplus · Accepted Answer

The freezing point depression can be calculated using the formula ΔT_f = i * K_f * m, where i is the van't Hoff factor (2 for KCl), K_f is the freezing point depression constant, and m is the molality of the solution. First, calculate the molality: moles of KCl = 5.0 g / 74.55 g/mol = 0.067 moles; molality = 0.067 moles / 0.550 kg = 0.122 m. Then, ΔT_f = 2 * 1.86 °C m^-1 * 0.122 m = 0.45 °C. The freezing point is depressed, so the change is negative: -0.45 °C.

Calculate the Freezing Point of a Solution Containing 5