How to Separate a Mixture of Salt from Sand


Quick Answer

To separate salt from sand, add water to the mixture, decant the sand particles and evaporate the water. Salt and sand form a heterogeneous mixture, which can be separated by physical means.

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How to Separate a Mixture of Salt from Sand
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Full Answer

The following equipment pieces are needed to separate salt from sand:

  • Two glass beakers or pans
  • Bunsen burner or heating source
  • Tripod stand
  • Glass stirring rod or spoon
  • Evaporating basin
  • Eye protection

In addition, a filter paper and filter funnel may be needed depending on the process of separation of the mixture. Water is also required for dissolving the salt.

Steps for the Separation of Salt from Sand

Step 1: Place the Mixture in a Beaker
Take the salt-sand mixture and pour it in a beaker. The mixture should occupy less than a quarter of the volume of the beaker.

Step 2: Add Water
Gently pour water into the beaker. For ease of dissolution, the added water should be twice as much as the volume of the mixture.

Step 3: Stir the mixture
Using a glass stirring rod or a spoon, gently stir the mixture until all the salt particles dissolve. Since the solubility of elements is directly proportional to the solvent temperature, it may be prudent to gently heat the water to ensure faster dissolution.

Step 4: Decant
Place the beaker containing the mixture on a flat surface and leave it for five to ten minutes. This will enable the insoluble sand particles to settle at the bottom of the beaker.

Gently tilt the beaker and pour the salt-water mixture into the second beaker. To ensure no sand particles move into the second beaker, the use of a filter paper and funnel may be necessary.

Step 5: Dry the Sand Particles
Retrieve the sand particles from the beaker and spread them on a flat surface. Let the sand naturally dry out in an open space. If a filter paper had been used, carefully scrape off the sand particles from the filter paper and spread them on a flat surface for drying.

Step 6: Evaporation
Place the beaker containing salty water above a heating source. Allow it to get heated until all the water evaporates hence leaving behind salt powder. For faster evaporation, a pan may be used due to its wide surface area.

To form salt crystals, evaporate the water until the solution reaches its saturation state. The saturation level can be tested with the help of the glass stirring rod. On reaching the saturation state, the solution is left to cool without further heating hence resulting in the build-up of salt crystals. Therefore, salt can be separated from sand through dissolution, decantation and evaporation.

On the other hand, salt and sand can be separated with a less conventional method ‰ÛÒthe use of melting points. Salt melts at 1474 degrees Fahrenheit (801 degrees Celsius) while sand melts at 3110 degrees Fahrenheit (1710 degrees Celsius). In this regard, heating the mixture to temperatures above 1474 degrees Fahrenheit (801 degrees Celsius) will make the salt melt. Hence, decantation process can be used to separate the molten salt from the solid sand. Subsequent cooling of the molten salt will result in its crystallization. However, such higher temperatures make the separation of the two compounds impractical and expensive.

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