Separation of Sand and Common Salt

Experiment 1: SEPARATION OF SAND AND COMMON SALT

OBJECTIVE

SEPARATION OF SAND AND COMMON SALT IN PURE AND DRY STATE FROM ITS MIXTURE.

APPARATUS REQUIRED

1. Funnel
2. Filter Paper
3. Burner
4. Wire gauze
5. Test tube
6. Porcelain basin.

CHEMICAL REQUIRED

i. Sand and common salt
ii. Silver Nitrate (AgNO₃)

THEORY

When a mixture of a soluble and insoluble solid is dissolved into a proper solvent, one component gets dissolved, leaving behind another undissolved component. Then each component from the mixture can be separated by filtration followed by successive physio-chemical treatment.

Filtration is the process of separating the water-insoluble component of the solution using a porous medium like filter paper. The insoluble component remains in filter paper as residue. The soluble component obtained is called filtrate. The filtrate contains sodium chloride solution and pure sand is obtained by the washing of water and pure salt is obtained by evaporation of filtrate.

PROCEDURE

The mixture of sand and common salt is taken in a beaker and salt is dissolved in a minimum amount of water by slightly stirring. The mixture containing solution is allowed to settle down and decant off the supernatant clear liquid. The supernatant liquid is filtered and the salt solution is collected in a porcelain basin. The filtrate taken in the basin is slowly evaporated to get common salt. Water is added to the sand-containing beaker and the mixture again. If the filter gives white ppt with silver nitrate, then the residue is again washed with water. The filter paper is carefully taken out from the funnel and dried over the Bunsen burner. The salt obtained in the porcelain basin is taken out by using a spatula in filter paper.

PURITY TEST (AgNO₃ test)

TEST REACTION

AgNO_{3}+NaCl\rightarrow \underset{White\ ppt.}{AgCl} + NaNo_{3}

RESULT

Hence, the mixture of sand and common salt was separated in a pure and dry state.

CONCLUSION

A mixture of water-soluble and insoluble substances can be separated by filtration followed by evaporation.

PRECAUTIONS

i. Salt solution should be dissolved in a minimum amount of water.
ii. The solution should not come up to the rim of the Filter paper
iii. Heat should be gentle.
iv. Apparatus should be handled carefully.