Freezing Point Depression: How Much Salt Will Melt Ice?

Use the sliders to set the temperature and the thickness of ice on a road. The equation for freezing point depression is given by
where is Boltzmann's constant, is the standard freezing point for water (273K), is the molecular weight of water (18.02 g/mol), is the molality (mol solute/kg solvent), is the enthalpy of fusion for water (6000 J/mol) and is the freezing-point depression constant (1.86). This equation determines the amount of salt needed. The value is displayed numerically and graphically; also shown (in blue) is the amount of salt carried by the truck.


  • [Snapshot]
  • [Snapshot]
  • [Snapshot]


[1] R. Chang, Physical Chemistry for the Biosciences, Sansalito, CA: University Science Books, 2005 pp. 138–147, 507.
    • Share:

Embed Interactive Demonstration New!

Just copy and paste this snippet of JavaScript code into your website or blog to put the live Demonstration on your site. More details »

Files require Wolfram CDF Player or Mathematica.