Freezing Point Depression Problem
Step 1: Calculate the molality of the NaCl. molality (m) of NaCl = moles of NaCl/kg water. Step 2: Determine the van ‘t Hoff factor. The van ‘t Hoff factor, i, is a constant associated with the amount of dissociation of the solute in the solvent. Step 3: Find ΔT. ΔT = iKfm.
What does the freezing point depression equation represent?
Kf is the molal freezing point depression constant of the solvent (1.86 °C/m for water). m = molality = moles of solute per kilogram of solvent. i = the number of dissolved particles (Van’t Hoff Factor).
What is the value of KF?
The value of Kf for water is 1.86^o , calculated from glucose solution.
What unit is KF?
Kf is the molal freezing point depression constant of the solvent (1.86 °C/m for water). m = molality = moles of solute per kilogram of solvent. i = the number of dissolved particles (Van’t Hoff Factor).
How is freezing point depression used in medicine?
It is used to determine the level of osmotically appropriate body fluid in various chemicals dissolved in the blood using the relationship which a mole of dissolved substance reduces the freezing point of water by 1.86 °C (35.35 °F).
What causes depression in freezing point Class 12?
This is due to the lowering of the vapour pressure of the solvent by the addition of the nonvolatile solute. When a liquid is cooled from the point A, its vapour pressure decreases and at the point B, it freezes (solidifies). In case of a solution, since the vapour pressure is lowered, the freezing point decreases.
What is kb and KF in chemistry?
Kf is the depression in freezing point produced by 1 molal solution of a nonvolatile solute while Kb is the elevation in boiling point produced by 1 molal solution of a nonvolatile solute.
How do you calculate TF in chemistry?
Strategy:
Step 1: Calculate the freezing point depression of benzene. Tf = (Freezing point of pure solvent) – (Freezing point of solution) Step 2 : Calculate the molal concentration of the solution. molality = moles of solute / kg of solvent. Step 3: Calculate Kf of the solution. Tf = (Kf) (m)
What is Ebullioscopic constant?
Ebullioscopic constant (Eb) is the constant that expresses the amount by which the boiling point T b of a solvent is raised by a non-dissociating solute. Its units are K Kg mol-1. b is the molality of the solute.
What is meant by cryoscopic constant KF?
A cryoscopic constant is described as the freezing point depression when a mole of non-volatile solute is dissolved in one kg of solvent. The cryoscopic constant is denoted by kf. Freezing point depression refers to the lowering of the freezing point of solvents upon the addition of solutes.
What is the SI unit of molal depression constant?
As the S.I unit of ΔTB is kelvin and that of molality is mol/kg, the S.I unit of Kb is (K. kg.
