Freezing Point Depression Calculator Formula
Understand the math behind the freezing point depression calculator. Each variable explained with a worked example.
Formulas Used
Freezing Point Depression
delta_tf = vant_hoff * kf_const * molalityNew Freezing Point
new_fp = fp_pure - vant_hoff * kf_const * molalityVariables
| Variable | Description | Default |
|---|---|---|
kf_const | Cryoscopic Constant (Kf)(C-kg/mol) | 1.86 |
molality | Molality(m) | 0.5 |
vant_hoff | Van't Hoff Factor (i) | 2 |
fp_pure | Freezing Point of Pure Solvent(C) | 0 |
How It Works
How to Calculate Freezing Point Depression
Formula
delta_Tf = i × Kf × m
For water, Kf = 1.86 C-kg/mol. New FP = pure FP - delta_Tf.
Worked Example
0.5 m NaCl (i=2) in water.
kf_const = 1.86molality = 0.5vant_hoff = 2fp_pure = 0
- 01delta_Tf = 2 × 1.86 × 0.5 = 1.86 C
- 02New FP = 0 - 1.86 = -1.86 C
Ready to run the numbers?
Open Freezing Point Depression Calculator