Thinking
For my chemistry class, I chose to reflect on the thinking core competency through the solubility lab. Our goal was to find the Ksp of PbI2 by combining different concentrations of Pb+2 and I- together at room temperature and to obtain the approximate Ksp for PbI2 above room temperature. To find the Ksp of PbI2 at room temperature, we found the TIP of each test tube by calculating the concentration of each ion and multiplying them together in the correct ratio. We knew that the value of Ksp must be between the TIP of the last test tube forming a precipitate and the TIP of the first test tube that didn’t form a precipitate, which was between 1.4×10-8 and 3.2×10-8. To find the Ksp of the saturated solutions, the solutions that formed precipitates were placed on a hot plate until the precipitate dissolved. We knew that the first four test tubes were saturated since they formed precipitate which meant that the TIP value was larger than the Ksp value and the last two test tubes had a lower TSP value than Ksp since no precipitate formed. Knowing that a perfectly saturated solution has a minimum possible amount of precipitate, when the precipitate dissolved at the specific temperature the TIP equalled the Ksp value . We used the knowledge we learned in class, our thinking skills and the notes from the lab to apply our knowledge to find the value of Ksp. Something that we could have improved on is to observe our test tubes closer since we didn’t see the precipitate formed inside the fourth test tube so we had to place it on the hot plate after we had already tested the first three test tubes.