Question

If you had a bucket that contained a mixture of sand and seashells, how might you use the physical properties of the seashells to separate them from the sand?

Answer 1

Hint : We should always remember whether a substance will dissolve in another substance or not. If it dissolves, then it will give a clear solution whereas if it does not dissolve, it will form a suspension and the methods employed for separation will become easier. Sand is insoluble in water.

Complete Step By Step Answer:
Heavier components in a liquid mixture can be separated by sedimentation followed by decantation or by filtration.
Sedimentation followed by decantation: In a sand water mixture, sand is a heavy particle. Hence sand water mixture can be separated by sedimentation method. First, leave the sand water mixture undisturbed for some time. Then the heavier sand particles will settle down on the bottom of the container. The upper portion will be water and the lower portion will be sand. This process is called sedimentation. Then the water in the upper portion can be transferred into another container. This should be done very carefully without disturbing the lower part of the mixture. This process is called decantation. Then the sand particles will remain on the beaker and water on another beaker. Hence the sand water mixture is separated.
Filtration: in this method, the sand-water mixture is passed through a filter paper with fine pores. Sand particles are large in size. Hence it cannot pass through the filter that blocks the sand particles. But water can easily pass through the filter paper. Hence sand particles are retained on filter paper and sand water mixture is separated.

Note :
Sand also contains salts and other compounds. If the sand contains a salt that is soluble in water, then we cannot separate the salt from water using the first two methods. But, we can separate the salt and water by using distillation.