zalles_Exp2

zalles_Exp2 - Experiment 2 Scientific Measurement and Error...

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Experiment 2 – Scientific Measurement and Error Spring 2010 Name Nicole Zalles Lab Section 414 Point Summary (See Blackboard for detailed grading rubric) Superior Excellent Satisfactory Fair Poor Omitted Materials and Methods Results and Discussion •Description of data •Data Tables •Data Table Titles •Sample Calculations •Systematic Error •Random Error •Discussion of discrepancies Other Lab Technique TOTAL POINTS TA Comments/Suggestions:
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C HEMISTRY 101L R EPORT T EMPLATE EXPT. Scientific Measurements and Error 2 Introduction The purpose of this report is to determine the accuracy and precision of common scientific equipment. The purpose of the experiment is to learn how scientific measurements are carried out properly using an electronic balance and various pieces of volumetric glassware, and to acquire an appreciation of the significance of measurements. Materials and Methods The procedure for this experiment was taken from Chem 101L Lab Manual. The following procedure is one designed independently, but also referencing the Lab Manual. Calibrating the Pasteur pipet: Materials: Pasteur Pipet (w/rubber bulb) 4 Scintillation Vials (without the lids!) Electronic Balance Water Sharpie (or marker) Procedure: 1) In order to calibrate a Pasteur pipet to measure out exactly 1.0000mL, we first needed to find the exact value of the mass (g) of water to measure out. Using the calculation, the required mass of water was found to be around .9970g for water at 21ºC. 2) After zeroing out an electronic balance, the mass of each of the 4 scintillation vials (again without their lids) was measured and recorded. a. If wanted, for each new vial on the balance, zero out the balance with the vial on it). 3) Using the Pasteur pipet and bulb, the water was dropped into the scintillation vial while on the balance until it read the mass to be exactly equal to the mass of the vial + .9970 (OR! If the scale was zeroed to the vial, jut until it read .997 or so). 4) After the mass of the water was equal to what was desired, the pipet was emptied, and then used to suction out all the water in the vial. After which, the level at which the water leveled in the pipet was marked using a sharpie; this line shows the measurement of 1.0000 mL of liquid. 5) Performed steps 3 thru 4 for the remaining three vials, re-zeroing the balance for each new vial. 6) After all data (mass measurements and such) were recorded, the volumes, average volumes, and standard deviation of the volumes were calculated (see Table 6). Results and Discussion The goal of the first part of the experiment is to determine the precision of the electronic balances in the lab. The data used for analysis are summarized in Table 1.
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Table 1. Electronic Balance Weighing Sample Mass (g) Trial 1 Mass (g) Trial 2 Mass (g) Trial 3 Mass (g) Trial 4 Weighing bottle with lid 76.386 76.386 76.386 76.387 Weighing bottle without lid 53.019 53.019 53.019 53.019 Weighing bottle lid only 23.367 23.367 23.368 23.367 Weighing bottle with lid on different balance
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This note was uploaded on 02/24/2011 for the course CHEM 101L taught by Professor Austell during the Spring '08 term at UNC.

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zalles_Exp2 - Experiment 2 Scientific Measurement and Error...

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