Lab 13B

Prompt: Please read the rubric! It is how you will be graded! Include everything listed on the front page of the lab in the manual. Add a photo, too! :) You will rip off the pre-lab and hand it in separately.

Introduction: The purpose of this lab was to identify a solid substance just by using its solubility. This was done by using a graph of solubility's of a few options of what the substance could be, and then testing the solid in water under various conditions. Solubility is the maximum amount of grams of a solute that can be dissolved in a constant amount of solvent without becoming saturated. Saturated is the maximum amount of a solvent that can dissolve of a solute where if it tried to dissolve more a solid would form.

Procedure: To begin with we were told it was one of three salts(NaCl, NaNO3, KNO3) and we were given a graph of the solubility of each of the salts. We began by making a hot water bath at around 30 degrees celsius. We then heated a small beaker of 10 mL of water in the bath and began attempting to dissolve 5 grams of our mystery solid into the 10 mL. We were unable to do so at that temperature, so according to our graph it could not have been NaNO3. We then further heated it to around 50 degrees celsius and the solute dissolved into the water, so we were able to determine that is was KNO3.

Data:
At 30 degrees celsius we were unable to dissolve 5 grams of the salt into 10 mL of water.
At 45 degrees celsius we were able to completely dissolve 5 grams of the salt into 10 mL of water.

Discussion/ Concluding Summary: We identified the substance to be KNO3. We determined this by eliminating the other options. First we added 5 g. of the salt to 10 mL of water at 30 degrees celsius. We knew if it were NaNO3 it would easily be able to dissolve with no solid remaining. However the solution had solid remaining so we knew we could eliminate NaNO3. Next we increased the temperature to around 45 degrees celsius but kept the amount of solute and solvent the same. We knew if the solid was dissolved it would be KNO3 but if a solid was still remaining it would be NaCl. The solid dissolved so we knew it was KNO3. Solubility in solids increases with temperature because the liquid has more energy and it is easier to displace the solute and dissolve it.