Question

What are physical properties that can separate a mixture?

Answer 1

Examples might include

• Soluability
• Immiscibility
• Boiling point

Explanation:

Table salt `"NaCl"` dissolves well in water whereas sand- a mixture containing primarily quartz `"SiO"_2`- does not. The difference in the solubility of the two species enables their separation through filtration.

![http://www.rsc.org/learn-chemistry/content/filerepository/CMP/00/000/455/CCE-1-SeparatingASandAndSaltMixture.pdf]()

For example, to separate a mixture of sand and table salt, start by dissolving the solid mixture in water to form a `"NaCl"` solution that contains sand. The solution part shall pass through a piece of filter paper whereas sand will be trapped on the funnel. Evaporating the salt solution removes `"H"_2"O"` such that `"NaCl"` is restored to its crystal form.

Separation funnels (see diagram below) facilitates the separation of two immiscible liquids - liquids that don't dissolve in each other e.g., water and mineral oil.

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What if the two liquids dissolve in each other in significant amounts? Fractional distillation separates substances of different boiling points. For example, it is possible to isolate ethanol `"C"_2"H"_5"OH"` from its solution in water `"H"_2"O"`- the two liquids mix at any ratio due to their capabilities of forming hydrogen bonds- with the help of distillation given that ethanol boils at a temperature lower than that of water.

![https://commons.wikimedia.org/wiki/File:Fractional_distillation_lab_apparatussvg]()

In the particular setup shown in the diagram, the temperature of the mixture in the round-bottom flask is maintained between `78.37color(white)(l)°"C"` the boiling point of ethanol and `100color(white)(l)°"C"` the boiling point of water, such that ethanol vaporizes, leaves the mixture, condenses, and collects in the conical flask whereas water remains in the mixture.