CHM 113 Lab 2.docx - Percent Error of Laboratory Glassware...

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Percent Error of Laboratory GlasswareKhaled Alhashimi Tiauna DenmanBrianna McKissickSlade SchneiterLab TA: Sthitadhi MaitiWednesday, September 14, 2016 Lab Section: W3--Lab Group: 2Wednesday 8:30am-10:20amIntroduction
The purpose of this lab was to calculate the percent error of lab glassware and identify which instruments are more precise or accurate. Precision can be defined as data that is closely related due to unvarying conditions. Accuracy describes measurements that are near the true value. Being able to identify glassware with the lowest percent error is an important tool when doing experiments because it allows for the most exact results. The percent error was found for the following lab glassware, the 50 mL buret, 10 mL graduated cylinder, 125 mL erlenmeyer flask, and 50 mL buret, weighed with and without substances. The density formula (D=m/V) and percent error formula |accepted valueknown value|acceptedvalue×100were used throughout this experiment.The glassware used in laboratories have two main functions, to hold certain volumes and deliver certain volumes. Determining the numerical values of these materials is very important for the goal of this lab. To ensure the most exact and verifiable results, significant figures are used to provide the results with more accurate data. For this lab, measuring four significant figures of thecalculated measurements for the pipette, graduated cylinders and flask, and beaker would allow for more specific measurements. Because there are so many different instruments used in sciencelabs, it is important to know what kind of results each instrument will provide when doing calculations and making conclusions.Materials50 mL Beaker125 mL Erlenmeyer Flask50 mL Buret 10 mL Graduated Cylinder
ThermometerPlastic PipetteWeighing BoatGoggles Electronic BalanceProcedureTo begin this experiment, an empty 50 mL beaker was weighed on an electric balance andit’s mass was recorded four significant figures. The beaker was then filled with 40 mL of water and weighed again and the new mass was also recorded to four significant figures. Next, the mass of the beaker with the water and the mass of the beaker without the water was subtracted tofind the mass of the water. The density of the water was then calculated using the density formula (D=m/V) from the measured volume and the calculated mass obtained earlier. This process was then repeated three times for the 50 mL beaker. Once the density was found in each trial, the numbers were added up and divided by 3. The percent error was then calculated by

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