3. In this experiment, what four techniques will be used to separate the mixture of sodium benzoate and sand?

To separate a mixture of sodium benzoate and sand, you can use the following four techniques: 1. **Decantation**: This technique involves the separation of a mixture based on the difference in density between the components. Since sand is denser than sodium benzoate, you can pour the mixture into a container and let it settle. The sand will settle at the bottom, and the sodium benzoate solution will remain on top. Carefully pour off the sodium benzoate solution, leaving the sand behind. 2. **Filtration**: After decantation, if there is any remaining sodium benzoate solution that is not easily separated by decantation, you can use filtration to remove it. Place a filter paper in a funnel and pour the mixture through it. The sand will be retained on the filter paper, while the sodium benzoate solution will pass through. 3. **Evaporation**: Once the sand has been separated from the sodium benzoate solution, you can evaporate the solution to obtain the sodium benzoate. Place the sodium benzoate solution in an evaporating dish and heat it gently. As the water evaporates, the sodium benzoate will crystallize and can be collected. 4. **Recrystallization**: If the sodium benzoate obtained from evaporation is impure, you can use recrystallization to purify it. Dissolve the sodium benzoate in a suitable solvent (such as water) and then slowly cool the solution. The pure sodium benzoate will crystallize out of the solution, which can then be filtered and dried to obtain a pure product. By using these four techniques, you can effectively separate and purify the mixture of sodium benzoate and sand.