化学
已验证计算器，公式透明
Freezing Point Depression Calculator.
Calculates the freezing point depression of a solution based on the solvent's cryoscopic constant, the van't Hoff factor, and molality.
您的输入
工作原理
- 1
Enter the cryoscopic constant for your solvent.
- 2
Enter the van't Hoff factor (number of particles per formula unit).
- 3
Enter the molality of the solution.
- 4
The calculator multiplies Kf × i × m to get the depression.
kf * i * molality常见问题
What is the van't Hoff factor?
It is the number of particles a solute dissociates into. For non-electrolytes it is 1; for NaCl it is 2.
Why does adding solute lower the freezing point?
Solute particles disrupt the solvent's crystal lattice, requiring a lower temperature to freeze.
Can I use this for any solvent?
Yes, if you know the solvent's cryoscopic constant (Kf). For water it is 1.86 °C·kg/mol.
工作原理
Calculates the freezing point depression of a solution based on the solvent's cryoscopic constant, the van't Hoff factor, and molality.
- Enter the cryoscopic constant for your solvent.
- Enter the van't Hoff factor (number of particles per formula unit).
- Enter the molality of the solution.
- The calculator multiplies Kf × i × m to get the depression.
公式
此计算器背后的数学公式，供您核对结果。
Freezing Point Depression
The depression is the product of the van't Hoff factor, the cryoscopic constant, and molality.
Example:
Input: i=2, Kf=1.86, m=0.5
Calculation: 2 × 1.86 × 0.5
Result: 1.86 °C
实际应用场景
此计算在日常生活中的应用。
Antifreeze
Determine how much ethylene glycol to add to lower the freezing point of radiator fluid.
Example: Adding 1 mol/kg of ethylene glycol lowers water's freezing point by 1.86 °C.
De-icing
Estimate the effect of salt on ice melting temperature.
Example: Salt (NaCl) with i=2 lowers the freezing point twice as much as sugar.
Lab preparation
Prepare a solution with a desired freezing point for experiments.
Example: To get -3.72 °C, use 2 mol/kg NaCl in water.
提示与常见错误
Tips
- Use molality (mol/kg) not molarity (mol/L).
- For strong electrolytes, use the theoretical van't Hoff factor (e.g., 2 for NaCl, 3 for CaCl2).
- For weak electrolytes, the van't Hoff factor is less than the theoretical value.
- Check the solvent's Kf value; it varies (water: 1.86, benzene: 5.12).
Common Mistakes to Avoid
- Using molarity instead of molality.
- Forgetting to multiply by the van't Hoff factor for ionic compounds.
- Using the wrong Kf for the solvent.
假设与限制
- Use the stated inputs and units.
- Results are estimates for planning and education.
- Check measurements and source data before making an important decision.