Freezing Point Depression: How Much Salt Will Melt Ice?

temperature (K)

255.15

thickness of ice (m)

0

amount of salt: 0. grams

Use the sliders to set the temperature and the thickness of ice on a road. The equation for freezing point depression is given by

ΔT=k

2

T

f

MWm/Δ

H

fusion

=

K

f

m

,

where

k

is Boltzmann's constant,

T

f

is the standard freezing point for water (273K),

MW

is the molecular weight of water (18.02 g/mol),

m

is the molality (mol solute/kg solvent),

Δ

H

fusion

is the enthalpy of fusion for water (6000 J/mol) and

K

f

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.

References

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

Permanent Citation

Jessica Baker, Elena Romund, Taylor Coates

"Freezing Point Depression: How Much Salt Will Melt Ice?"
http://demonstrations.wolfram.com/FreezingPointDepressionHowMuchSaltWillMeltIce/
Wolfram Demonstrations Project
Published: April 19, 2019