Measurement and Uncertainty Lab

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School

Herzing University *

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MISC

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Chemistry

Date

Jan 9, 2024

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pdf

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Uploaded by MateRainMule41

11/19/23 Measurement and Uncertainty Activity 1 Data Table 1: Determination of Uncertainty in Lab Balance Trial Cup #1 Mass (g) Cup #1 Deviation from Average (g) Cup #2 Mass (g) Cup #2 Deviation from Average (g) 1 10.00 g 0.01 g 9.99 g 0.00 g 2 10.01 g 0.02 g 10.00 g 0.01 g 3 9.98 g 0.01 g 10.00 g 0.01 g 4 9.99 g 0.00 g 9.98 g 0.01 g 5 9.99 g 0.00 g 9.98 g 0.01 g Average 9.99 g 0.01 g 9.99 g 0.01 g Question 1. Suppose you continued Activity 1 using a third plastic cup of the same type. Would you expect the average deviation from the average mass to be the same or different? Explain your answer. If you use a third plastic cup in the same experiment, whether the average deviation from the average mass will be the same or different depends on a few things. If everything is very accurate and the new cup is similar to the first two cups, the average deviation may be similar. This is if the conditions and measurements stay the same. But if there are differences in the new cup or if something changes in how you're doing the experiment, the average deviation could be different. Things like how well the balance is set up, how the cups are handled, and if the cups are all the same can affect the results. In scientific experiments, it's important to keep things the same to get reliable results. If things change, the average deviation might show those changes. Activity 2 Data Table 2: Determination of Uncertainty in Common Glassware 10-mL Graduated Cylinder 50-mL Graduated Cylinder 25-mL Erlenmeyer Flask 250-mL Beaker Mass of empty glassware 10.83 g 30.00 g 23.15 g 46.25 g Estimated volume of water 7.12 ml 24.00 ml 17.00 ml 52.25 ml

11/19/23 Measurement and Uncertainty 10-mL Graduated Cylinder 50-mL Graduated Cylinder 25-mL Erlenmeyer Flask 250-mL Beaker High volume interval 7.15 ml 24.05 ml 17.03 ml 53.15 ml Low volume interval 7.10 ml 23.95 ml 16.98 ml 52.15 ml Uncertainty 0.05 ml 0.10 ml 0.05 ml 0.50 ml Mass of glassware with water 17.92 g 54.00g 54.00 g 40.75 g 98.45 g Mass of water 7.09 g 24.00 g 17.60 g 52.20 g Question 2. Which piece of glassware has the highest degree of precision? Why? The 10-mL Graduated Cylinder and the 25-mL Erlenmeyer Flask are the most precise because they have the smallest uncertainty, which is like a measure of how close we expect our measurements to be. Smaller uncertainty means our measurements are likely to be closer together. This means that these two pieces of glassware are the best at giving us accurate measurements among the options. Measurement and Uncertainty Back Activity 3 Data Table 3: Determination of Accuracy in Common Glassware 10-mL Graduated Cylinder 50-mL Graduated Cylinder 25-mL Erlenmeyer Flask 250-mL Beaker Mass of water in Activity 2 7.09 g 24.00 g 17.60 g 52.20 g

11/19/23 Measurement and Uncertainty 10-mL Graduated Cylinder 50-mL Graduated Cylinder 25-mL Erlenmeyer Flask 250-mL Beaker Current water temperature 21 °C Density of water at room temperature 0.9980 g/mL Calculated volume of water 7.11 ml 24.05 ml 17.67 ml 52.27 ml Question 3. Accuracy is gauged by comparing the measured value of a known standard to its true value. Assuming the mass of the water represents a standard for the true volume of water, which piece of glassware has the highest degree of accuracy? Why? Accuracy means how close your measurement is to the correct value. If we use the mass of the water as the correct value, we can see which glassware gives us a measurement that is closest to what we expect. 1. 10-mL Graduated Cylinder: • Calculated Volume: 7.09g0.9980g/mL ≈ 7.12mL0.9980g/mL7.09g ≈ 7.12mL 2. 50-mL Graduated Cylinder: • Calculated Volume: 24.00g0.9980g/mL ≈ 24.06mL0.9980g/mL24.00g ≈ 24.06mL 3. 25-mL Erlenmeyer Flask: • Calculated Volume: 17.60g0.9980g/mL ≈ 17.66mL0.9980g/mL17.60g ≈ 17.66mL 4. 250-mL Beaker: • Calculated Volume: 52.20g0.9980g/mL ≈ 52.27mL0.9980g/mL52.20g ≈ 52.27mL 1. 10-mL Graduated Cylinder: • We measured about 7.12 mL. It's quite close to what we expected. 2. 50-mL Graduated Cylinder: • We measured about 24.06 mL. It's close, but not as close as the 10- mL one. 3. 25-mL Erlenmeyer Flask:

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11/19/23 Measurement and Uncertainty • We measured about 17.66 mL. It's pretty close, similar to the 10-mL one. 4. 250-mL Beaker: • We measured about 52.27 mL. It's close, but not as close as the 10- mL or 25-mL ones. So, the 10-mL Graduated Cylinder seems to be the most accurate because its measurement is very close to what we expected.