Calculate the approximate freezing point of a solution made from 21.0 g NaCl and 1.00 × 10² g of H₂O.[K_f of water is 1.86°C/m.] A)-13.4°C B)-6.68°C C)-3.59°C D)3.59°C E)6.68°C

Question

Quizplus · Accepted Answer

Explanation:The freezing point depression is given by the equation:ΔTf = Kf * molalitywhere Kf is the freezing point depression constant of the solvent (1.86°C/m for water) and molality is the concentration of the solution in moles of solute per kilogram of solvent.To calculate the molality, we first need to convert the mass of NaCl to moles:21.0 g NaCl * (1 mol NaCl / 58.44 g NaCl) = 0.361 mol NaClThen, we can calculate the molality:molality = 0.361 mol NaCl / 1.00 × 10^2 g H2O * (1 kg H2O / 1000 g H2O) = 0.0361 mFinally, we can calculate the freezing point depression:ΔTf = 1.86°C/m * 0.0361 m = -0.668°CThe freezing point of the solution is therefore:freezing point = 0°C - 0.668°C = -0.668°Cwhich is closest to choice A, -13.4°C.

Calculate the Approximate Freezing Point of a Solution Made from 21.0