Introduction
Have you ever mixed sand and salt together and wondered how you could separate them again? If you had to separate them, would you have nightmares of tiny tweezers, a magnifying glass and hours spent picking grains of salt and sand apart? Don't be afraid, there is another way! Using the differences in solubility between salt and sand, you can find the simple "solution" to this problem.
Background
Chemistry for the most part is the study of matter and how it behaves and interacts with other kinds of matter. Everything around us is made of matter. One important property that matter has is solubility. We think about this when we dissolve something in water. If a chemical is soluble in water, then when you add it to water it will dissolve, or disappear. If it is not soluble, then the chemical will not dissolve and you can see it, either suspended in the water or at the bottom of the container.
When a chemical is dissolved in a liquid, such as water, it creates a solution. In a solution, the liquid is the solvent, and the soluble chemical that is added to and dissolves in the liquid is the solute. Even though a solvent dissolves a solute, the latter blends in but is still there. If you evaporated all of the liquid from the solution, you would be left with the dry solute again. In fact, this is how salt is processed in giant salt flats where seawater is slowly evaporated, leaving behind huge amounts of sea salt.
Materials
• Strainer (optional)
• Salt
• Sand
• A napkin
• Magnifying glass
• Two glass jars with lids
• Measuring cup
• Water
• Teakettle or pot
• Two spoons
• Stove and oven
• Funnel
• Coffee filter
• Spoon
• Oven mitts
Preparation
• If the sand has a lot of debris in it, use a strainer to strain out the large debris and purify the sand.
• Place some salt and sand separately on a napkin and, using the magnifying glass, closely examine the salt and sand. What do you notice? How does the size, shape and color of the grains of sand compare with the grains of salt?
• Be careful when using the stove and oven, and when handling the boiling water. An adult should help you with these steps.