In this lab we had to find the identity of an unknown salt. Salt have individual solubilities, so by dissolving them at different temperatures, we could tell what compound they were. We used water as the solvent, and dissolved the salt as the solute. We referred to the solubility curves to identify the solid.
Procedure:
First, we referred to the solubility curve of NaNO3, KNO3, and NaCl. We decided that if we dissolved 7 grams in 10 grams of 80 degree celsius water, then it cannot be NaCl because the graph shows that at 80 degrees 7 grams of NaCl would dissolve. After eliminating NaCl we had to test a point on the graph between KNO3 and NaNO3 so we added 7 grams to 10 grams of water at 30 degrees to test if it would dissolve. If it dissolves it then it is NaNO3 but if it cannot dissolve all 7 grams then it is KNO3.
Quantitative Data:
Trial 1- 10 grams of water
7 grams of salt
heated to 80 degrees celsius
Trial 2 - 10 grams of water
7 grams of salt
heated to 30 degrees celsius
Qualitative Data:
Trial 1- All of the salt dissolved so it is not NaCl
Trial 2- The salt did not dissolve therefore it is KNO3
Conclusion:
Because the 7 grams of salt did not dissolve in 10 grams of water at 30 degrees we knew that it could not be NaNO3 because it would have dissolved according to the solubility curve. Also, it is KNO3 because it 7 grams of salt dissolved in 10 grams of water at 80 degrees, which it would not have if it were NaCl according to the solubility curve. Therefore we narrowed it down to KNO3. For most solids, increasing the temperature increases the solubility. Keeping the temperature of the solution at constant was very challenging but we managed to keep it level during our experiment.
Heating the solutions in a hot bath!
No comments:
Post a Comment