Observations and results
When 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.
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A Soluble Separation Solution from Science Buddies
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2 Comments
Add CommentThe first step of the procedure says, "...shake until the salt and sand are completely mixed into the liquid." At this point there are no liquids involved. The only materials in the jar are air, sand and salt.
Reply | Report Abuse | Link to thisA more sophisticated experiment that I used to do with my 8th graders is fractional crystallization where 2 soluble solids with similar solubilities at room temperature but very different solubilities at a higher temperature (like sodium chloride and potassium nitrate) are dissolved in the same volume of water then heated to the boiling point of the water then filtered and allowed to cool overnight. Most of the residue is undissolved sodium chloride whereas most of the potassium chloride dissolves in the hot water. The next day, students discover that when the dissolved potassium nitrate solution is allowed to cool overnight, gigantic crystals of potassium nitrate have precipitated as the solution cooled. A class favorite.
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