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.
More to explore
Matter from Chem4Kids.com
Solutions from Chem4Kids.com
A Soluble Separation Solution from Science Buddies
This activity brought to you in partnership with Science Buddies