Procedures
Materials:
12 empty cuvettes, a cuvette holder, a ruler with mm measurements,
2-10ml graduated cylinders, 0.35 solution PbCl2, 0.35 solution NaI
Procedures:
1. Pour 4 ml PbCl2, and 1 ml NaI into three cuvettes and label as group A.
2. Pour 3 ml PbCl2, and 2 ml NaI into three cuvettes and label as group B.
3. Pour 2ml PbCl2, and 3 ml NaI into three cuvettes and label as group C.
4. Pour 1ml PbCl2, and 4 ml NaI into three cuvettes and label as group D.
5. Place all 12 cuvettes in a cuvette holder, allowing them to be sitting at an upright position (completely vertical and perpendicular to the desk).
6. Allow the precipitate to settle completely to the bottom of the cuvettes.
7. Once the precipitate has settled, measure the height from the bottom of the cuvette to the top of the precipitate in millimeters and record your results in Data Table A.
Data
Table:
Data Table A
Constants and Givens: amount of solution, resting position of the cuvettes, Temperature, concentration of the PbCl2 solution, concentration of the NaI solution.
Observations: The greatest amount of lead iodide precipitate seemed to form when the amount of lead chloride was slightly less than the amount of sodium iodide.
Results
Sample Calculations:
Results Table/Graph:
Interpretation: The greatest amount of precipitate formed when the amount of lead chloride was 2 mL and the amount of sodium iodide was 3 mL.
Error Propagation: The cuvettes might not have been stored completely upright, and thus would have made the measurement of the precipitate inaccurate. There was no standard way to measure the amount of precipitate in the cuvettes, and thus would have made the measurements erroneous.
Conclusion
Conclusion: My hypothesis was correct because the greatest amount of precipitate formed when the amount of lead chloride was 2 mL and the amount of sodium iodide was 3 mL.
Evaluation of Procedures:
Improvements: The cuvettes might not have been stored completely upright, but that was due to a lack of proper equipment, and this error could have been eliminated by an improvement of equipment. There was no standard way to measure the amount of precipitate in the cuvettes, and marking all of the cuvettes at standard intervals could have eliminated this error.
