A water solution containing an unknown quantity of an unknown nonelectrolyte solute has a freezing point of -0.21 Celsius. What is the molality of the solution? Kf=-1.86C/m
To find the molality of the solution, we can use the formula:
ΔTf = Kf * m
Where:
ΔTf is the freezing point depression, which is the difference between the freezing point of the pure solvent and the freezing point of the solution.
Kf is the freezing point depression constant for the solvent.
m is the molality of the solution, which represents the number of moles of solute per kilogram of solvent.
In this case, we are given that the freezing point depression (ΔTf) is -0.21 Celsius and the freezing point depression constant (Kf) is -1.86°C/m for water. We need to find the molality (m).
Rearranging the formula, we have:
m = ΔTf / Kf
Substituting the given values:
m = -0.21°C / -1.86°C/m
Now we can calculate the molality:
m = 0.113 mol/kg
So, the molality of the solution is 0.113 mol/kg.
To find the molality of the solution, we will use the formula:
ΔTf = Kf × m
Where:
ΔTf = change in freezing point
Kf = freezing point depression constant (in this case, -1.86 °C/m)
m = molality of the solution
Given:
Freezing point depression (ΔTf) = -0.21 °C
Kf = -1.86 °C/m
Rearranging the formula, we can solve for molality (m):
m = ΔTf / Kf
Plugging in the values:
m = (-0.21 °C) / (-1.86 °C/m)
m ≈ 0.113 m
Therefore, the molality of the solution is approximately 0.113 m.
delta T = Kf*m
Substitute and solve for m.