How does salt melt ice?

Answer 1

It lowers the freezing point as it dissolves in the water. So, for example, if the air temperature is -2C, putting salt on the ice might lower the freezing point of the salt / water mix to -5C. The air temperature is now higher than the freezing point, so the icy salty mix melts.

Adding salt will have no effect at very low temperatures.

Answer 2

The salt makes the water in the ice less concentrated, so you have a solution of sorts. Since salt has a (much) higher melting point than water does, adding salt to ice raises the melting point of the entire solution. So the ice melts. I think of it as sort of like taking the average of two melting points when you combine two compounds.

Answer 3

Salt decreases the the freezing point of Ice and thus the ice melts when it is at 0 degrees. That is why it melts the ice.

Answer 4

When salt, or any other impurity, is added to ice, it's melting point is lowered. So instead of 0 degrees Celsius, it is now -2 degrees Celsius.

As the temperature of the ice is still 0 degrees Celsius (above the new melting point), it must change into the liquid state and hence it melts.

Answer 5

Its quite complicated and couldn't be sure to get it right (although I'm sure many people have got it very wrong!) but it because it lowers the melting point of water. I think this is to do with the formation of ice crystals and the effect of the salt crystals/ions on the forces between water molecules which cause the water molecules to stick together as ice.

Answer 6

Salt solution has a lower melting point than water, so when the salt dissolves into the ice it lowers the melting temperature so melting it.

Answer 7

the key is that salt does not form part of the ice (i.e. in the ice you have pure water) so when adding salt to ice, the ions (Na+ and Cl- if you're adding NaCl) simply dissolve in the liquid water that is surrounding the ice.
As a consequence, the chemical potential of water in the liquid is lowered and the equilibrium is displaced.
It can be easily visualized in the following way: now there is a gradient in concentration of water molecules (more concentrated in the solid than in the liquid), so water molecules will tend to go from the solid to the liquid... What you see macroscopically is that ice melts.

Answer 8

It lowers the freezing point, thus making the ice melt at a higher temperature.

Answer 9

Salt is sodium chloride.

The freezing point of a solution of sodium chloride is lower than that of water, hence adding salt makes it a solution of sodium chloride which will need even more lower temperatures in order to freeze.

Its the same thing when we add salt to water when we're making pasta and want the water to boil faster........by adding salt we are making a solution of sodium chloride which has a lower boiling point and will therefor require less heat to make t boil.

Answer 10

Salt is a good store of heat. It is used in thermal batteries. Adding salt to water allows heat to be absorbed faster, so the freezing point of the solution is lowered.