3120 c post lab 1.docx - Kim Dao CHM 3120C Sec 001 Post Lab...

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Kim DaoCHM 3120C Sec 001Post Lab 1: Weighing Procedures and Glassware CalibrationIntroduction: In analytical chemistry, the quality of results is solely based on the accuracy of measurements. Inthis experiment, students successfully learned the different methods of weighing samples as well as calibrating glassware. Both the pan balance method and analytical balance method were used in this lab to demonstrate weighing procedures. The difference between pan balance and analytical balance method is, pan balance can take the sample directly for measurement whereas the analytical balance will require taking the weight difference (Koppal). This is usually done by taking a weighing instruments weight and deducting it from the total of the object + weighing instrument. Students also practiced on a volumetric (transfer) pipe and burette. The goal is to obtain measurement accuracy. Other lab techniques will be practiced such as determining mean and standard deviation values. Throughout this lab, it is important to take in consideration errors and identifying potential errors. This will overlap with the concept of “tolerance”. Tolerance is used to set an acceptable error range within an experiment (“Tolerance and Measurement Accuracy..”). Students will be calculating the tolerance by comparing the measured water volume vs. the actual amount volumeof water that is set to be dispensed using a burette. For example, based off the table in the manual on page 17, if we were dispensing 10 mL of water we would expect no more and no less than the tolerance of ±0.02. The acceptable range would fall between 9.98 mL and 10.02 mL.

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