As a chemist, you have numerous methods at your disposal to separate sand and salt. However, the simplest approach involves combining two basic separation techniques we’ve previously discussed: filtration and evaporation. Through filtration, you can isolate the sand from the saltwater solution. And by subjecting the saltwater solution to evaporation, you’ll recover the salt in its solid form.
Here is how to go about it:
Apparatus and Chemicals You Need
- Bunsen burner
- Ring Stand
- Wire Gauze
- Tripod Stand
- Filter Funnel
- Filter Paper
- Evaporating Dish
- Beaker
- Stirring Rod
- Sodium Chloride (Common Salt)
- Sand
Procedure
- Make a mixture containing equal amounts of salt and sand.
- Place about 20g of the mixture in a 500ml beaker.
- Add about 200ml of the water into the beaker and stir with a stirring rod.
- Boil the mixture to dissolve as much as possible. You can add more water if necessary.
- Pour the mixture into a filter funnel fitted with filter paper (as shown in the previous filtration setup). Collect the filtrate in another beaker.
- Transfer the filtrate to an evaporating dish and heat over a steam bath (as shown in the previous evaporation setup) until all the liquid evaporates.
- Allow the hot concentrated filtrate to cool for more crystals to form.
Observation and Discussion
Sand is insoluble in water and doesn’t dissolve even after boiling. When you filter the mixture, sand is left as residue on the filter paper. The filtrate is a solution of sodium chloride in water since sodium chloride is soluble in water. When you evaporate the filtrate over a water bath, you are left with pure sodium chloride (or common salt) in the form of a white powder. You then allow the hot concentrated filtrate to cool to allow more crystals of sodium chloride to form.
