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5 How to Prepare a Semiformal Lab Report The following sections should be included in lab report in this order and they should be stapled together firmly, including printouts, if any. A your hardcopy of your lab report is to be turned in at the beginning of the lab period, one week from the date the lab was performed. Title Page/Cover page (typed), (2 points): The title page should clearly display: The name of the experiment Your name (larger font and bold) Name of your lab partner (normal font and not bold) The date the experiment was performed The course number and section Objective(s) (typed), (5 points): Bottom of the title page; identify the main objective of the experiment. You should be able to cover this section in one brief paragraph, i.e. two or three well written sentences. You may paraphrase statements found in lab manual but do not copy them. This section is written in third person and present tense. Experimental, (5-10 points): The experimental section of your lab consists of copies of the pages in your lab notebook which contain the data for the experiment. Results, (25-30 points): Sample Calculations: This section contains an example of each calculation you used to produce the results asked for in the lab manual. Many times your lab will include five or six different calculations/equations you will need to use, and each calculation will be performed three or more times because you run multiple samples. Do not include every calculation; just include one of each type. These sample calculations should be typed using a word processor's math and symbol inserts. Hand written calculations will be accepted but if the TA can't read your work, points will be deducted. Neatness counts! Almost every data point you collect will have a unit associated with it. Units must be included on all your data to receive all the points. Data Analysis: This section contains an analysis of the data collected in lab. It should be typed and in paragraph form. The lab manual will give questions that will help guide this analysis. All answers to these questions must be backed up by your data and explained fully. This section is written in the third person and past tense. Tables must be generated in a spreadsheet or word processing program. See the table below for a "good" example. Each column needs to be labeled, including units. Tables need to have a caption which indicates what is represented in the table. How to Prepare a Semiformal Lab Report 6 Table 3. Concentration of Arsenic Species (jgg 1 as elemental arsenic) in Soil Spiked with As(III) Sequentially Extracted with 100 mmol L-1 H3PO4 and 100 mmol L=¹ NaOH. Species H3PO4 extracta NaOH extracta totalb As(III) 3.0 + 0.2 2.6 + 0.2 5.6 +1 0.3 DMA ND ND ND MMA ND ND ND As(V) 12.7 +1 0.9 2 I 2 15 +1 2 Totalb 15.6 +1 0.9 5+ 2 21 I 2 amean + standard deviation (n = 3), b+ term is square root of sum of squares, not detected All graphs are to be produced using Graphical Analysis or Excel with axes labeled. All graphs need to be referred to in your data analysis section with an explanation of what conclusions can be drawn from your graph. When copying and pasting graphs from a spreadsheet program such as Excel, you will need to edit the figure so that it conforms to the appropriate format. An example of a figure that the spreadsheet software typically produces is given in Figure 1, together with commentary on how to modify this output so that the figure appears as shown in Figure 2. Put equation in the text Extra title not needed Extra box not needed / Remove R²value Plot of Absorbance vs Concentration Remove lines 0.7 V = 0.0197x+0.0123 0.6 R² =0.9987 0.5 0.4 0.3 Series1 0.2 Linear (Series1) 0.1 Just absorbance Remove this not absorbance material units 10 20 30 40 Tick marks should be Concentration of copper Need units on this axis inside graph space Use the correct number of significant digits on axis labels Figure 1. Typical plot from a spreadsheet program with comments about what needs fixing. How to Prepare a Semiformal Lab Report 0.700 0.600 0.500 0.400 0.300 0.200 0.100 0.000 0.0 5.0 10.0 15.0 20.0 25.0 30.0 35.0 Copper concentration g mL-1 Figure 1. Flame atomic absorption calibration for copper. The line, which is fit by least squares regression, is y= 0.0197x + 0.0123, where yis absorbance and x is concentration in g mL²¹. Figure 2. Figure showing the result of fixing the problems shown in Figure 1. You will notice that the student who produced this graph has used for micro (and not u) and has found a way to make the -1 a superscript. One way to fix the limitations of the formatting of text in the spreadsheet program is to create a text box in the word-processing program and overwrite the label after the plot has been copied into the word-processing document. For the situation described in Figure 1, it is appropriate to fit a trend line because the underlying relationship between the two variables is expected to be linear, but this is not always the case. Consider an experiment in which the concentration of chloride was monitored as a function of the distance from the highway. The results of this experiment are shown in Figure 3. If the underlying relationship is not known then simply display the points without a trend line. Do NOT connect the dots! 120 100 80 60 40 20 50 100 150 200 250 Distancefrom highway in feet Figure 3. Chloride concentration in soil as a function of the distance from the highway. Conclusion, (5 points): This should be a very short section, i.e. one paragraph containing three or four sentences that discuss the following items (not all will apply to every experiment); How to Prepare a Semiformal Lab Report 8 Was the objective for the experiment met? (always include this one) If applicable, the unknown was The accuracy of your experimental results should be included if you have a known value to compare your results to. The precision of your data; if the lab requires you to determine a value (like a rate constant for a reaction) and you experimentally determine the value three different ways, you should include the mean and the standard deviation for your data. This section is written in third person and present tense. References, (3 points): Cite complete references for any information that you draw on The CHEM 2130 Lab Manual will always be the first reference. If you look up a value or some other reference, cite it here. Format for book citations: Author 1; Author 2; Author 3; etc. Chapter Title. Edition Number; Series Information (if any); Publisher: Place of Publication, Year; Volume Number, Pagination. Grading Sheet: Include a copy of the grading sheet stapled to the back of your lab report. 9 1: Kinetic Factors Problem Statements: What factors can be used to change the rate of a reaction? Are these factors predictable from the balanced equation? The Reaction: Oxalic Acid In this experiment Permanganate you will be lon studying Reduced the by reaction between permanganate, Mn04 and oxalic acid, C2O4H2, in acid solution. The overall balanced reaction equation is: 2 MnO4¹(aq) + 5 C2O4H2(aq) + 6 H+(aq) 2 Mn2+(aq) + 10 CO2(aq) + 8 H2O(I) Your lab notebook should contain the following data and copies of those pages are then included in the Experimental (10 pts) lab report. I. Watching the Reaction a. Obtain a dropper bottle for each of the stock solutions 0.0014 M K2MnO4, 0.20 M C2O4H2 and 2.0 M H2SO4. Put about 30 mL of distilled water in a 100 mL beaker. Get a clean plastic pipet for the distilled water. You will be making various mixtures of these four solutions by counting drops. Be careful that the droppers are not switched between solutions during any of the work. b. Take three clean, distilled-water rinsed, large test tubes and label them 1 through 3. You will be doing experiments three runs at a time and need to keep track of each run. These can be supported in a test tube rack or in a 250 mL beaker while you observe them. Viewing them against a white background is advised. C. Make up the three solutions as described below. Mix each by flicking the bottom of the tube while holding its top securely. Observe these solutions for about 10 minutes and record your observations. You should include a data table with these volumes in your lab notebook. Drops of Stock Solutions Run # KMnO4 H2O H2SO4 C2O4H2 1A 15 15 15 2A 15 25 5 3A 15 10 15 5 II. Data Collection: Effect of H+ Concentration a. In the experimental runs from here on, you will be timing how long it takes for all the MnO4 1 ions to react by watching the color fade. The recommended procedure is as follows: Dump the current contents of your test tubes into your waste beaker and rinse each a few times with about 1 mL of water. The rinse water can go down the drain. Shake out excess water. Add the stock solutions to each tube as called for except for the C2O4H2. Then add the time when the color drops of C2O4H2 to each tube, has faded. mix by flicking, and record this as the starting time. quickly Also record the b. Sample Data Table: This data data written table should be copied into your laboratory notebook. You will not receive credit for on this page. 1: Kinetic Factors 10 Drops of Stock Solutions Times Run # KMnO: H2O H2SO4 Starting Ending Total 1B 15 20 5 5 20056 28 15 10 15 5 65 8.31 3B 15 o 25 5 175 III. Data Collection: Effect of C2O4H2 Concentration a. Make up the runs below using the procedure outlined in part II above. b. Sample Data Table: Drops of Stock Solutions Times Run # KMnO4 H2O H25O4 C2Och2 Starting Ending Total 1C 15 10 15 5 2C 15 5 15 10 3C 15 15 15 IV. Data Collection: Effect of Copper Metal a. Do the runs as outlined below using the procedure in part II. Again put everything together except the C2O4H2, then start counting time with its addition. Use copper strings for this experiment. Bunch each into a very loose ball that can be submerged in the solution and still have all of the string exposed to solution. b. Sample Data Table: Drops of Stock Solutions Times Run # KMnO4 H2O H2SO4 C2O4H2 Cu Starting Ending Total 1D 15 10 15 5 2D 15 10 15 5 1 string 3D 15 10 15 5 2 strings V. Data Collection: Effect of Temperature a. Using a hot plate, make a hot water bath in a half-filled 250 mL beaker. Heat the bath until it is 40-50*C. Maintain this temperature interval by heating or allowing the bath to cool. b. runs below except for the C2O4H2. Put the 5 minutes Make up to of the get the solution to temperature. Remove one test run tubes from the into bath, the bath quickly for add several drops mix, and return to the bath. When that reaction is done, repeat the the experiment on the other run. 1: Kinetic Factors 11 c. Sample Data Table: Drops of Stock Solutions Times KMnO4 H2O H2SO4 C2O4H2 Temp Starting Ending Total Run # 15 10 15 5 40-50°C 1E 15 10 15 5 40-50°C 2E Results (20 pts) answers to these questions should be included in your results section. However, this should be The written as a discussion in paragraph form not simply as a list of answers. Be sure to use your data/observations as examples and explanations for your answers. Offer explanations for the observations in "I. Watching the Reaction". Did all runs show a change? If not, why not? Did those that changed do so instantly? If not, why not? (4 pts) What effect does increasing the concentration of H+ ion have on the rate of the reaction? Use your data to support your answer. Does this seem reasonable? Explain your reasoning in terms of what the molecules and ions may be doing. (4 pts) What effect does increasing the concentration of oxalic acid have on the rate of the reaction? Use your data to support your answer. Does this seem reasonable? Explain your reasoning in terms of what the molecules and ions may be doing. (4 pts) What effect does the presence and amount of Cu metal have on the rate of the reaction? Use your data to support your answer. Does this seem reasonable? Explain your reasoning in terms of what the molecules and ions may be doing. (4 pts) What effect does increasing the temperature have on the rate of the reaction? Use your data to support your answer. Does this seem reasonable? Explain your reasoning in terms of what the molecules and ions may be doing. (4 pts) Conclusion (10 pts) The conclusion should be a short (5-10 sentences) paragraph that answers the objective of the lab. In other words, for this experiment, the conclusion should summarize the following: The factors that can be used to change the rate of this redox reaction. Which factors are more effective? Which are less effective? Explain your reasoning. Could some or all the factors you found to affect the reaction rate have been predicted from knowing only the overall reaction? Explain your reasoning. References Abraham, M. R.; Pavelich, M. J. Kinetic Factors - Exp. K-1. Inquiries Into Chemistry, 3rd ed.; Waveland Press: Long Grove, IL, 1999; pp 199-202. 1: Kinetic Factors Kinetic Factors Determining Factors that Affect Rate of Reaction predicted of Purpose: reaction TO analyze factors that overall affect can be rate and to see if these outcomes by the chemical equation. I I Run# Drops of stock Solution KMn04 15 6 HaD H2507 Cabhtt Times 1B 20 15 P 5 2B 5 10 Starting 0.00s Ending Total 15 5 11.07 13.07 3B 15 D Dubles 25 5 8-31 8:31 175 4: 4 3:57 II Effect of CattaDa concentration of II Run# Drops of Stock sountion Kmno4 H2O IC 15 H2504 an Ca04172 Times R 2C 10 15 15 5 starting 5 OS Ending Total ng 1 15 10 4:10 15 15 163 4:10 ngs 3C 4:26 ion 15 4:10 405 4:35 III Effect of Copper metal 3:55 hb A I Run# Drops of Stock Solution XI Kmh04 ID H2O 15 H2504 C2Ofta Times 10 Cu rD 15 15 5 Starting 10 3D 15 1:01 Ending Total 15 10 15thing 1713 6:00 4.59 15 15 3=03 grings 1:50 IV Effect of Temperature 1:20 3:15 3:55 Run # Kmn04 Drops of H2O Stock Solution batl ) COO IE H2504 L204H2 Times 15 2E 16 15 Temp. h for 15 IV 5 15 40-50°C 5 starting US Ending 355 Total ickly 40-50°C 05 35s e, rep X(First table for orgentations) 37s 375 IA Drops of stock 15 H2O 2A 15 1750 is 25 to Observations 3A 15 DO 15 5 10 iritial initial pink woldring no change is 5 initial pinklooding g-no classeclear pink coloning in no change 10 VII f procedure absentations D 1. obtain 0.00/41 M Kamno4, 17 d 5. 11 D. 20mgHH204 / 2.1 U 2. obtain BOML of DI water in rc beaker. t of e B. Obtain three large test tubes labeled / through 3. - 4 make solutions described in Table I. only and facled n = mix and bnsche for 10 minutes. 1B 5. make solutions in table II. 3B faded first, 2B 2nd 7B Time until color fades and record BB data (Remember to add 6 Repeat experiment with data from 1stning first; 7 and 0 close Eft Table III Record data. 7. Repeat exp. with data from Table IV. Run Remember to bunch up Lopper. 11 Record data. to 2C 8 Acquire hot plate and heat 3C to 40-50°C 9. make solutionswithout (20)H2. 01 Effi Heat solutions in bath 7 remove, I add Cruylta quicking, and replace J Run: in nath. Record data in Table IV ID Votton 20

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