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The post-lab questions provided are SIMILAR to questions you may encounter in your lab manual (link). These questions will provide you with a step-by-step guide on how we approached the problem. You can use this guide and the data you recorded to help answer the questions.Any given examples with values will be with mock values. Use of these values will almost assuredly give you nonsensical calculations. They are only meant to illustrate the logic.

 

question 1

What was the most accurate method measuring volume in your experiment?

Note that the mass of water was determined by subtracting the mass of the beaker from the mass of the beaker with water. This is done for all instruments (graduated cylinder, pipet, and buret) used to transfer water. Using the density of water (1 g/mL), the most accurate instrument will be the one closest to the expected value.

For example 1 gram for 1 mL, 2 grams for 2 mL, etc. This should be taken from your data sheet Part C. Dispensing Liquids. The sample data shown have all three instruments delivering 0.100 grams. That means that all are of the same accuracy if 0.100 mL was delivered.

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question 2

Give the precision of each instrument using numbers and their appropriate units.

The precision of an instrument will be dependent on the instrument you use and possibly the manufacturer. Look on the instrument you are using. It will sometimes give values that indicate its precision. If it is not noted, a rule of thumb is to take half the smallest gradation on the instrument (e.g., if the smallest gradation is 0.1 then ± 0.05)

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question 3

Why was the instrument in question 1 most accurate (use information from question 2)?

Give your answer using the information in question 1 and 2 along with factors that may make instruments more or less accurate and/or precise. For example, the the method of transfer using the graduated cylinder may result in residual liquid not being transferred and contributing in less precision (stuck at the bottom).