You want to purchase a salt to melt snow and ice on your...

You want to purchase a salt to melt snow and ice on your sidewalk. Which one of the following salts would best accomplish your task using the least amount: $\mathrm{KCl}, \mathrm{CaCl}_{2}, \mathrm{PbS}_{2}$, $\mathrm{MgSO}_{4}$, or $\mathrm{AgCl} ?$

Key Concepts

Freezing Point Depression

This is the phenomenon where the addition of a solute, such as a salt, to a solvent, like water, lowers the temperature at which the solvent freezes. It is a key principle in understanding how salts can melt ice by reducing water’s freezing point.

Colligative Properties

These properties depend on the number of solute particles relative to solvent molecules rather than the nature of the solute itself. In the context of de-icing, colligative properties explain how dissolving salts in water affects the freezing point, making them effective for melting ice.

Ionic Dissociation

This concept involves the breakup of ionic compounds into their constituent ions when dissolved in water. The number of particles produced by dissociation directly influences freezing point depression, as more ions yield a greater effect in lowering the freezing point.

Solubility

Solubility refers to the ability of a substance to dissolve in a solvent, which is critical for salts used in melting ice. A salt must be highly soluble in water to efficiently produce the ions necessary for significant freezing point depression.

Eutectic Point

The eutectic point is the lowest temperature at which a homogeneous mixture of substances can remain liquid. In de-icing applications, salts with lower eutectic points can be effective at melting ice at lower temperatures, thereby using less material to achieve the desired effect.

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