lab 1 Questions

# lab 1 Questions - addition such a small volume of liquid...

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Experiment One Questions 1. If an experiment were to call for adding exactly 3.1 mL of a given solvent I would recommend weighing the solvent on a balance and then using the solvent’s liquid density to calculate the volume of the liquid from its mass. A standard pipette would not be able to draw up that much liquid. In addition, pipettes are not accurate when dealing with high volumes of liquid. The graduated cylinders that students are provided in lab are only accurate to within .25 mL. Because we need 3.1 mL, a student would have to measure the solvent somewhere in between 3.0 and 3.25 mL. This technique would promote inaccurate results. 2. If an experiment were to call for adding approximately 1 mL of a given solvent I would recommend estimating the volume using a Pasteur pipette. Based on the data from the first part of the lab, a student can accurately estimate 1 mL of a solvent by using a pipette. Measuring the solvent using a graduated cylinder would work as well, but might take more time. In
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Unformatted text preview: addition, such a small volume of liquid can be inaccurate in a graduated cylinder due the meniscus effect and liquid sticking to the walls of a graduated cylinder. The pipette is a smaller container and therefore is not affected by these two problems as harshly. Weighing the solvent using a graduated cylinder would take extra steps, because the student would have to convert the weight of the liquid to volume using the solvent’s density. Each step would unavoidably have human error, which would be compounded if a student were to weigh the liquid. 3. 4. A student should use a new Pasteur pipette each time he/she uses a different solvent because different solvents chemically react and can affect the results of the experiment. If for example, HCL and NaOH were used in the same pipette, the solvent in the pipette would be neutralized to some extent and would not yield accurate results. 5....
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