Lab report #1 - professor: Holland Lab TA: Trammel PDF

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professor: Holland
Lab TA: Trammel...

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Taylor Herrera Lab Partner: Amanda Oldham Section: 04 Lab Report

Chem 200, Experiment 1 Use of Volumetric Equipment Procedure A. Using a pipet After filling a 400 mL beaker with water, set aside for later use. Then fill and drain a pipet with water out of a 150 mL beaker. While doing so, look to see if droplets of water stay on the inside on the pipet or not. Using the water set aside in the beginning, use a 25 mL volumetric pipet and deliver 25 mL of water each into three 125 mL Erlenmeyer flasks. The precise mass of water in each beaker will be determined by recording the mass of each flask before and after adding the water. Calculate average and standard deviation of the three volume measurements. B. Using a graduated cylinder Fill up a graduated cylinder precisely to the 100 mL mark with water. The mass of water will be determined by recording the mass of the beaker before and after the addition of water. The cylinder will then be emptied and the process will be repeated two more times for consistency. Calculate average and standard deviation of the three volume measurements along with absolute difference and percent difference. C. Using a Buret After pouring 15 to 20 mL of water into a 50 mL beaker, place a buret in a buret clamp, close the valve and place a waste beaker beneath the buret. Then pour 10 mL of water into the buret from the 50 mL beaker, cover all surface area of the buret with solution by moving it in a circular motion. Pour in another 10 mL of solution and repeat the process. Fill the buret with water to above the 1.00 mL mark by pouring in more water. Record both initial and final volumes. Record the initial buret reading as a volume between 1.00 and 10.00 mL. Place a tared flask under the buret and transfer 35 mL of water to record as the final buret reading. Repeat with two more flasks. Calculate density of water in each trial, along with percent difference between experimental average density and theoretical value. D. The Volume of one drop of water Add 30 drops of water to a 50 mL beaker using a medicine dropper. Record room temperature and the density of water at this temperature. Then calculate the average mas of one drop of water using the density value that is closest to the current room temperature. *All water is DI water

Experimental Data A. The temperature of the room was 21 C. From table 1 in my lab manual (p.28), I found the density of water at room temperature was 0.99799 g/mL. Part A Mass of the flask (g) Mass of flask + H2O (g)

Trial 1 74.114 98.932

Trial 2 78.782 103.635

Trial 3 82.860 107.731

B. The temperature of the room was 21 C. From table 1 in my lab manual (p.28), I found the density of water at room temperature was 0.99799 g/mL. Part B Mass of cylinder (g) Mass of cylinder + H2O (g)

Trial 1 49.655 149.193

Trial 2 49.655 148.900

Trial 3 49.655 149.016

C. The temperature of the room was 21 C. From table 1 in my lab manual (p.28), I found the density of water at room temperature was 0.99799 g/mL. Part C Trial 1 Trial 2 Trial 3 Mass of flask (g) 83.531 74.882 79.051 Initial buret volume 1.00 3.00 9.00 (mL) Final buret volume 36.00 39.00 40.00 (mL) Mass of flask + H2O 117.498 109.371 111.513 (g) D. The temperature of the room was 21 C. From table 1 in my lab manual (p.28), I found the density of water at room temperature was 0.99799 g/mL. Part D Mass of beaker (g) Mass of beaker + 30 drops of water (g)

Trial 1 28.974 30.467

Calculated Results: Part A Trial 1 Trial 2 Mass of water (g) 24.818 24.853 Volume of water 24.868 24.903 (mL) Average Volume of Water Standard Deviation (mL): 0.027 Absolute Difference: 0.10 Percent difference: 0.40%

Trial 3 24.871 24.921

Part B Trial 1 Trial 2 Mass of water (g) 99.538 99.245 Volume of water 99.738 99.445 (mL) Average volume of water at standard deviation (mL): 0.1475 Absolute difference (mL): 0.419 Percent Difference: 0.41%

Trial 3 99.361 99.561

Part C Trial 1 Volume deviation 35 (mL) Mass of water (g) 33.967 Density of water 0.9704 (g/mL) Average Density (g/mL): 0.9918 Absolute difference: 0.00619 Percent Difference: 0.62%

Trial 2 36

Trial 3 31

34.489 0.9580

32.462 1.047

Part D Mass of 30 drops of water (g) Average mass of 1 drop of water (g) Average volume of 1 drop of water (mL)

Trial 1 1.493 0.0498 0.0499

Discussion/Questions 1. Part A gave the most accurate results with a percent error of only 0.40%. Part A was also the most precise because the average volume was closest to the actual volumes. Part A was done using a pipete. 2. The results discussed in question 1 reflect systematic error because it took three trials in each A, B, and C to find the results. During the three trials, the measurements might not have been exactly the same, which is why the volumes are all slightly different. In every experiment there is going to be random error, which explains why our percent error is not 0%. 3. If the solutions were at 50C, the mass of water delivered from the 25 mL pipet would be 24.7g. .9881 = m/25mL .9881x25 = 24.7g 4. The density of water measured with the buret in part C was not very precise because all three trials yielded different numbers, and even though it was the least accurate out of part A and part B, I still think it was an accurate measurement considering the percent error was only 0.622%. 5. If a 25 mL pipet or a 100 mL graduated cylinder was used to make further measurements, I would use the same volume for each calculation. The calibration procedure would reduce systematic error because there would be more replications of the experiment....