Question:

Does Salt Melt or Freeze Things?

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I don't know. My teacher told me it freezes things, but then I see (when it snows) a big truck pouring salt on the streets to help melt it. I remember a classmate asking this, but I just can't remember the answer

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4 ANSWERS


  1. maybe you miss heard your teacher bit it actually asorbs stuff like you no when you buy something it has that little packet in it that is similar to salt but that absorbs moist in the air.


  2. it lowers the freezing point - so it melts ice - that's why you throw it on an icy sidewalk.

  3. Salt has a lower freezing point than water, so during winter, if salt is poured on the road, snow is not likely to freeze, but rather stay in the liquid form. Now, that doesn't mean salt will not freeze, if it is a the freezing point of the salt, it will freeze.

    You can do an experiment on your own, take some salt water and put it in the freezer, IT WILL FREEZE.  

  4. Salt, when spread on ice, will cause it to melt.  It works when there is at least a minute amount of liquid water present.  If there is no liquid water than nothing will happen.

    It works for two reasons.  The dissolving process is exothermic.  The heat generated helps to melt the ice.  Then the additional water that is formed dissolves the salt and forms a solution that has a lower freezing point than pure water.  This is known as a colligative property.  

    DT = ikm

    where DT is the change in temperture of boiling or freezing

    i is the van't Hoff factor

    k is the freezing point depression constant or boiling point elevation constant

    m is the molality

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