Expt 1 Template Fall 23

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University of California, San Diego *

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Chemistry

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Dec 6, 2023

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CHEM 7L – Expt 1, Fall 2023 DUE Thursday Oct. 13, 2023, 10:00 p.m. Experiment 1 Lab Report: Precision and Accuracy Data/results should also be input directly into Canvas. Author: Date: TA Name: This report should be 5 pages; you may delete instructions in red font. Do not adjust the margins, font sizes, etc. of this template. Save this document with filename Expt1_Author_TAname, where Author is your name, and TAname is your TA’s name. ABSTRACT and SUMMARY of Results : (3 pts) The majority of this section has been pre-written to serve as an example for future reports. Replace the blank regions with your content in blue . Watch significant figures (the temperature should be reported to the nearest 0.5 °C; standard deviations should have one or two sig. figs.). If there is a range or multiple values for temperature and density, indicate the range or values. Three pieces of glassware (50-mL beaker, 10-mL graduated cylinder, and 10-mL volumetric pipet) were used to dispense a target volume of 10.000 mL water. The actual volume of dispensed water was determined by measurements of mass and the known density of water. The temperature of the water was __________°C , and the corresponding density at this temperature from a reference table was _________ g/cm 3 . Three replicate measurements for each piece of glassware were performed. Based on these measurements, the most accurate piece of glassware was the _______________ , with a % error of _______________. The most precise glassware was the _________________ , with a % relative standard deviation of ____________. Measurements from the entire laboratory section were collected for the graduated cylinder, and these results were compared with measurements made individually. SUMMARY OF RESULTS Individual Trials ( n = ________ ) Beaker: Avg ± stdev (ml) = ________± _________ml %RSD (two sig figs) = ________% %Error, relative to 10.000 mL target (two sig figs) = ________% Grad. Cyl: Avg ± stdev (ml) = ________± ________ml %RSD (two sig figs) = ________% %Error, relative to 10.000 mL target (two sig figs) = ________% Pipet: Avg ± stdev (ml) = ________± ________ml %RSD (two sig figs) = ________% %Error, relative to 10.000 mL target (two sig figs) = ________% Laboratory Section ( n = ________ ) for graduated cylinder only Grad. Cyl: Avg ± stdev (ml) = ________± ________ml %RSD (two sig figs) = ________% %Error, relative to 10.000 mL target (two sig figs) = ________% Copyright 2023 by Rodolphe Jazzar UCSD - Not for distribution Lab Report 1, Page 1

CHEM 7L – Expt 1, Fall 2023 DUE Thursday Oct. 13, 2023, 10:00 p.m. EXPERIMENTAL : This section has been pre-written to serve as an example for future lab reports. If anything unexpected or unusual happened during the experiment (e.g. the balance was fluctuating, sample was spilled, etc.), describe that in the space below the paragraph. Otherwise, leave this space blank. Glassware was cleaned with water and prepared for the experiments. Three glass vials with caps were rinsed with water and dried with a low-dust tissue (“Kimwipe”) to remove residual water. Each vial and cap was labeled, and each pair of vial+cap was weighed using an analytical balance. Three pieces of glassware were also rinsed with water: a 50-mL beaker, a 10-mL graduated cylinder, and a 10-mL volumetric pipet. Approximately 100 mL of deionized water was placed in a beaker, and the temperature of the water was allowed to equilibrate until it was within 1 °C of the temperature of the room. The temperature was recorded using a thermometer. Once equilibrated, water was placed in the 50- mL beaker up to the 10-mL mark, and this 10 mL of water was then poured into one of the pre- weighed glass vials. The vial was capped with the corresponding lid. This procedure was repeated two more times. Each of the three capped vials with water was weighed, and the mass was recorded. After the masses were recorded, the water was discarded, and the vials were dried. The same process was repeated with the 10-mL graduated cylinder, and with the 10-mL volumetric pipet (type TD). The three capped vials with water delivered from the graduated cylinder were individually weighed, and then emptied and dried for the final set of measurements with the pipet. For the volumetric pipet, a rubber bulb was used to draw water into the pipet and dispensed into the empty vials; the pipet was allowed to gently touch the wall of the vial to deliver the entire contents of the pipet per the proper use of a TD-type pipet. The data for the three trials of the graduate cylinder were tabulated for each student in the section, and this collective data for the graduate cylinder for the entire lab section were analyzed. The following anomalies occurred during the experiment: Copyright 2023 by Rodolphe Jazzar UCSD - Not for distribution Lab Report 1, Page 2

CHEM 7L – Expt 1, Fall 2023 DUE Thursday Oct. 13, 2023, 10:00 p.m. Individual Data : (3 pts) Fill in the table with your data (in blue ). Watch significant figures (sig figs should be reported based on instrument and mathematical operations). Beaker Temperature of water (in ºC) ºC Density of water at indicated temperature above (in g/mL) g/mL Mass of empty vial+cap (g) Mass of vial+cap with H 2 O (g) Mass of H 2 O (g) Vol. of H 2 O from mass and density (mL) Beaker, trial 1 g g g ml Beaker, trial 2 g g g ml Beaker, trial 3 g g g ml Graduated Cylinder Temperature of water (in ºC) ºC Density of water at indicated temperature above (in g/mL) g/mL Mass of empty vial+cap (g) Mass of vial+cap with H 2 O (g) Mass of H 2 O (g) Vol. of H 2 O from mass and density (mL) Gr. cylinder, trial 1 g g g ml Gr. cylinder, trial 2 g g g ml Gr. cylinder, trial 3 g g g ml Pipet Temperature of water (in ºC) ºC Density of water at indicated temperature above (in g/mL) g/mL Mass of empty vial+cap (g) Mass of vial+cap with H 2 O (g) Mass of H 2 O (g) Vol. of H 2 O from mass and density (mL) Pipet, trial 1 g g g ml Pipet, trial 2 g g g ml Pipet, trial 3 g g g ml Copyright 2023 by Rodolphe Jazzar UCSD - Not for distribution Lab Report 1, Page 3

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CHEM 7L – Expt 1, Fall 2023 DUE Thursday Oct. 13, 2023, 10:00 p.m. Graduated cylinder sample calculations (individual data) : (8 pts) Show your calculations for the individual trials for the graduated cylinder. You must use equation editor . The formulae are provided. Do not truncate values during the calculation to avoid rounding errors; show at least one more sig. fig. than you are allowed ; The proper number of sig. figs. is reported in the final answer only . Graduated cylinder: Calculation of the average: ´ x = ∑ i = 1 n x i n Graduated cylinder: Calculation of the sample standard deviation: x i −´ x ¿ 2 ¿ ¿ ∑ i = 1 n ¿ ¿ s = √ ¿ Graduated cylinder: Calculation of the % RSD: %RSD = s ´ x × 100% Graduated cylinder : Calculation of the % error: % error = | ( experimental value ) −( truevalue ) truevalue | × 100% Summary of the Graduated Cylinder for individual data Copyright 2023 by Rodolphe Jazzar UCSD - Not for distribution Lab Report 1, Page 4

CHEM 7L – Expt 1, Fall 2023 DUE Thursday Oct. 13, 2023, 10:00 p.m. Note – this is NOT a calculation, you should use correct sig figs again. Average and sample stdev (correct number of sig. figs. based on manual Part A3): Avg = ________ml Stdev = ________ml %RSD and %error (correct number of sig. figs. based on quotient rule): %RSD (two sig figs) = _______% %error (two sig figs) = _______% DISCUSSION : (6 pts) One paragraph should include all of the following:  Restate the goals of the experiment, and summarize the results of the experiment.  Compare the accuracy and precision for each type of glassware, and make sure to refer to the average, sample standard deviation, % error, and %RSD in this comparison.  For the graduated cylinder, compare the results for the individual set of three measurements, with the pooled dataset from your full lab section. Address the following question: are there any advantage(s) of having the larger dataset? Copyright 2023 by Rodolphe Jazzar UCSD - Not for distribution Lab Report 1, Page 5