A Soluble Separation Solution
Key Concepts
Chemistry, solubility, water, temperature
IntroductionHave 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.
This activity is not appropriate for use as a science fair project. Good science fair projects have a stronger focus on controlling variables, taking accurate measurements, and analyzing data. To find a science fair project that is just right for you, browse our library of over 1,200 Science Fair Project Ideas or use the Topic Selection Wizard to get a personalized project recommendation.
BackgroundChemistry 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
Preparation
Procedure
Extra: Many different chemicals have different degrees of solubility. By adding different amounts of salt, sugar or baking soda to water you can see how soluble each chemical is. Just add each chemical, one teaspoon at a time, to a half-full glass of water until you notice that it no longer dissolves when you stir it. Which chemical is the most soluble (dissolves the most into the same amount of water); which chemical is the least soluble?
Extra: How might temperature affect the solubility of a chemical? Try dissolving the same amount of sugar in hot water, room-temperature water and ice-cold water, using the same amount of water each time. What happens? Can you think of other variables that might affect solubility?
Observations and ResultsWhen you added the boiling water, did the salt dissolve or disappear? After drying in the oven, did the salt appear in the second jar and mostly the sand was in the first jar?Salt is soluble in water whereas sand is insoluble (not dissolvable ) in water. If sand were soluble in water, we would not have beautiful sandy beaches! Because of this, when the boiling water was added to the mixture of salt and sand, the salt should have dissolved, or disappeared, whereas the sand stayed visible, creating a dark brown solution with possibly some sand particles stuck on the walls of the jar. Temperature can affect the solubility of a chemical, and in the case of salt in water the hot temperature of the boiling water improved the salt's ability to dissolve in it. The dissolved salt should have easily made its way through the coffee filter and into the second jar whereas the muddy, undissolved sand particles became stuck on the coffee filter (possibly mixed with some salt as well). After the liquid in the two jars was evaporated in the oven, the salt in the second jar should have become apparent again, mostly as a crusty white substance along the sides and the bottom of the second jar. More to ExploreMatter from Chem4Kids.com
CreditsTeisha Rowland, PhD, Science Buddies
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Key Concepts
Chemistry, solubility, water, temperature
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