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E. Coli Lab Report

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Safety Protocols E. coli is a bacterium capable of being transmitted from one person to another. To ensure that the bacteria used in this experiment were not transmitted to other places, items, or organisms, several safety protocols were followed. When streaking bacteria and handling mannitol and xylitol solutions, the experimenter wore an apron, nitrile gloves on both hands and plastic protective goggles. After each set of plates were prepared, the experimenter removed the gloves from both hands without skin contact and thoroughly washed their hands for approximately 20 seconds with soap and warm water. Throughout the entire experiment the experimenter was cautious also to avoid contacting bacteria with eyes, mouth, or open wound. …show more content…

coli were labeled as bacteria that should not be examined or touch without permission from the supervising teacher. Although the strain of E. coli used in this experiment was harmless, to avoid transmitting the bacteria to other organism, the experimenter handled the E. coli for caution (see Appendix H, I, J, K). After the trials were completed, a 1:9 bleach to water solution was poured on top of the prepared agar plates. This safety precaution was used to kill the bacteria in preparation of disposal of the agar plates. After the bleach solution was applied to the agar plates, the solution stayed on the agar plates for approximately 5 minutes. The bacteria on the agar plates turned a yellow color after the five minutes and were disposed of. Each safety precaution implemented in this experiment was to ensure the safety of the experimenter, and other …show more content…

The volume is 10 mL when the pipette is full. To calculate percent uncertainty: (0.02 mL)/(10 mL)*100=0.2%.
Calculating the percentage uncertainty for a 250 mL volumetric flask
The uncertainty for a 250 mL volumetric flask is ± 0.15 mL. The volume is 250 mL when the flask is full. To calculate percent uncertainty: (0.15 mL)/(250 mL)*100=0.06%
Calculating the percentage uncertainty for a 50 mL graduated cylinder
The uncertainty of the graduated cylinder is ±0.5 mm. The volume of the substance measured is 50 mL because the density of water is 1 g/〖cm〗^3 and the mass is 1 gram per milliliter. To calculate percent uncertainty: (0.5 mm)/(50 mL)*100=1%
Calculating the percentage uncertainty for an electronic scale
The uncertainty for an electronic scale is ±0.01 because the scale measures into the hundredths place. The volume of the sugars is V=M/D, where V is volume, M is mass, and D is density. V=(25 g+25 g)/(1.52 g⁄〖cm〗^3 +1.5 g⁄〖cm〗^3 ), V=16.56. To calculate percent uncertainty:0.01/16.56*100=0.06%
The percent uncertainty for beakers was not calculated. The beakers were only used for storing the solutions. Therefore, the accuracy of the beakers did not affect the outcome of the

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