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In cold countries, it is a common phenomena to add salt to melt or clear snow. However, only specific salts are being commercially. So my question is that why only sodium chloride and $\ce{CaCl2}$ are used for addition to snow, to melt/clear it?

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Salts will lower the melting point of snow or ice. $\ce{NaCl}$ is chosen because it is cheap.

Edited: Salt with more total ions is more effective. $\ce{CaCl_{2}}$ is the one of the most available salt with 3 total ions. $\ce{MgCl_{2}}$ is another option. Some crude $\ce{NaCl}$ produced from sea water directly contain $\ce{Ca}$ and $\ce{Mg}$ salt and can be used to melt ice.

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  • $\begingroup$ But depression in freezing point is a colligative property which should only depend on the number of solute particles and not the nature of the solute. Right? $\endgroup$
    – Jas
    Apr 29 '14 at 10:18
  • $\begingroup$ For ideal solution, there is the Blagden's Law: $\Delta T_{f} = K_{F} * b * i$ where $K_{F}$ is a constant, $b$ is the molarity and i is the van 't Hoff factor, which is 2 for $NaCl$ and 3 for $CaCl_{2}$. $\endgroup$
    – Coconut
    May 2 '14 at 17:34
  • $\begingroup$ @IanFang, minor correction: $b$ is molality, not molarity. $\endgroup$
    – Greg E.
    May 2 '14 at 18:45
  • $\begingroup$ @GregE. you are right. Thank you for correction. $\endgroup$
    – Coconut
    May 3 '14 at 15:00
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Sodium chloride is used because it is cheaper than most of the others salts.

Sodium Chloride $\ce{NaCl}$ / Industrial Salt : US $65-95 / Metric Ton

potassium chloride industrial grade: US $90-130 / Metric Ton

Prices taken from http://www.alibaba.com/

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