Post-Lab Questions

Directions:

Answer each of the following questions. All work must be shown to receive credit for questions involving calculations. All questions are weighted equally.

1. When transferring water between the beaker and graduated cylinders, did the measured volume change? Use an example from your personal data to support your answer. Explain why the measured volume may have changed.
2. All the glassware used in this lab can measure small volumes. However, which size graduated cylinder is best for measuring volumes smaller than 10 mL accurately? Explain your reasoning.
3. Examine the class data collected in Part B of the lab. Would you describe the data as having high or low precision? Use the standard deviation to justify your answer and explain what the standard deviation indicates about the spread of the measurements.
4.  A 25.00 mL volumetric pipet is used to transfer 25.0 mL water to a 25.0 mL graduated cylinder five separate times. Assume 100% of the water is transferred each time. The volume in the graduated cylinder is read to be 24.0 mL, 24.0 mL, 23.9 mL, 24.0 mL, and 24.1 mL. Would you consider the graduated cylinder to be accurate, precise, both, or neither? Explain your answer using the concepts of accuracy and precision.
5. a – If you were asked to prepare 12.0 mL of a solution as accurately as possible, which piece of glassware & corresponding size(s) from this lab would you choose? Explain why.

b -If you were asked to prepare 120.0 mL instead, which piece of glassware & corresponding size(s) from this lab would you choose? Explain why.