Question

Describe how a pure sample of sodium chloride could be obtained from a mixture of sodium chloride and sand.

Answer 1

To separate and acquire pure sodium chloride from a mixture with sand, dissolve the mixture in water, filter to remove the insoluble sand, then evaporate the water to recover the pure sodium chloride.

Step-by-step explanation:

To obtain a pure sample of sodium chloride from a mixture of sodium chloride and sand, we can take advantage of the fact that sodium chloride is soluble in water while sand is not.

The process involves dissolving the sodium chloride in water to separate it from the sand and then recovering the dissolved sodium from the solution. Here is a step-by-step method:

1. Add water to the mixture of sodium chloride and sand and stir the mixture to allow the sodium chloride to dissolve. The dissolution of sodium chloride can be understood through the process shown in Figure 5.1.8, where the sodium chloride dissociates into ions and spreads throughout the water due to ion-dipole interactions.
2. Once the sodium chloride is dissolved, we carry out filtration. The sand, being insoluble, remains as a residue on the filter paper, effectively being separated from the sodium chloride solution that passes through the filter.
3. Dry the sand residue to obtain it as a separate component.
4. Evaporate the water from the sodium chloride solution. This can be done by heating the solution until all the water has evaporated, leaving behind the pure sodium chloride.

As a result of these steps, we are able to acquire a pure sample of sodium chloride free from sand. This exemplifies a common laboratory separation technique based on the different physical properties of the substances involved.