Additionally, we needed to find the different...

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Precision and Accuracy Erin Rafferty Koby Jones Logan Gililland Marina Barto TA: Ricardo Ortiz Wednesday 10:30 am
Introduction: Since there are several different pieces of equipment in the laboratory used for measurement, it can be difficult to decide which is the most accurate and precise for certain labs. In this specific lab, we were expected to familiarize ourselves with the laboratory glassware by accurately measuring liquid volume, using a balance, and comparing our results. We were also asked to compare our results with theoretical volumes which were measured from the mass and theoretical density of water. In order to solve this problem, we developed a procedure or plan which would be referenced throughout the experiment to ensure that we were on the right track. Our plan was to perform several measurements to find the mass of water and then use the theoretical densities in order to calculate the volume of the glassware. The temperature of the water used for the experiment was 22.5 so the theoretical density was 0.997655 ( 2 ). This would help us to find the percent error and determine which glassware would be the most accurate. The educational purpose of this lab is to become more familiar with the lab material so that we could use it for future experiments. This lab encouraged us to find masses, volumes, and densities of different objects to further our knowledge of the density equation: Density = Mass/Volume We also found several different measurements and learned how to put all of our information into tables and accurately calculate percent error at the end of each calculation. Percent error informs us of the experimental measurement accuracy: % Error = X 100 Accepted V alue Experimental V alue Accepted V alue | |
Additionally, we needed to find the different concentrations and volumes of stock solutions and compare them as ratios in order to determine the volume of the stock solution needed for this experiment. The following dilution equation was used for part 4 of this experiment: V V M 1 1 = M 2 Procedure/Experimental: First, all the materials were gathered: a 600mL beaker, a 50mL beaker, a graduated pipette, a buret, and a 10mL graduated cylinder. The 600mL beaker was filled with approximately 300mL of distilled water. The water temperature of the water was determined to be 22.5 °C using a thermometer. The 50mL beaker and 10mL graduated cylinder were cleaned, dried, and weighed while empty. Their masses were recorded in Tables 1 and 2 respectively. The 50mL beaker was filled to about 30mL with water from the 600mL beaker and its experimentally measured volume was recorded in Table 1. The full beaker was then weighed and its mass was recorded in Table 1. This was repeated for 2 more trials in order to include variation. The actual volume of the water was then calculated using the equation for density. The percent error for the experimentally measured volume was calculated. Next, the 10mL graduated cylinder was filled with approximately 7mL of water from the 600mL beaker and its experimentally measured 2

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