Page I-ix / Lab Notebooks, Lab Reports, Graphs, Parts Per Thousand Information on Lab Notebooks, Lab Reports and Graphs

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1 Page I-ix / Lab Notebooks, Lab Reports, Graphs, Parts Per Thousand Information on Lab Notebooks, Lab Reports and Graphs Lab Notebook: Each student is required to purchase a composition notebook (similar to the picture on the right) for recording data during lab. These notebooks may be purchased at stores like Walmart or Big Lots for about a dollar. Notebooks that have non-removable pages might be acceptable as a substitute; talk to the instructor for details on eligibility. Once you have a lab notebook, sequentially number the pages in the upper corner. Make sure you use ink for numbering the pages as well as for the lab notes (pencils smudge all too easily.) Leave the first several pages blank for a table of contents as you go along (this notebook can be used during all three quarters of general chemistry.) Each lab should begin on a new page in your lab notebook. Start the page with the title of the lab, the names of your lab partner(s), and the date. Be sure to include anything necessary for completing the lab report for this lab. This will include, but is not limited to, all unknown numbers, relevant data points, measurements (with units), temperatures, etc. Make sure you include a description of what the measurement is for (i.e. Mass of metal = g). Use tables when appropriate, and be sure to include key calculations. Here are two sample data entry styles for use with your lab notebook: (my thanks to Joyce Sherpa!) The Journal Style : Step a) In the fume hood, we added 20 drops of concentrated (16 M) HNO 3. The solution immediately began bubbling profusely with copious amounts of brown gas being emitted. We continued to swirl the beaker, which became quite warm, in the hood for 2 minutes until there was no evidence of brown gas being emitted and there was no copper left in the beaker. The beaker contained a clear, bluish-green solution. The Engineering Style : a) +20 drops 16 M HNO 3 in the hood (brown effervescence, heat) Stir 2 min in hood (Cu disappeared, blue-green solution) Both styles are acceptable; find the lab notebook style which best fits you. If an error is made, use a single line to cross out the incorrect statement. Never remove any pages from your lab notebook! Recording information on loose scraps of paper (or stapling pages to the lab notebook) is not appropriate and should be avoided. Have your lab notebook signed by the instructor at the end of the lab. This is especially important if you make-up the lab with another instructor. Lab Notebooks will be collected at the end of the term for grading. Omission of the above information will result in lost points. Page I-ix / Lab Notebooks, Lab Reports, Graphs, Parts Per Thousand

2 Page I-x / Lab Notebooks, Lab Reports, Graphs, Parts Per Thousand Lab Reports: Each student must turn in his or her own lab report. Lab reports must be typed and complete for credit. Each lab report should include: your name your lab partner(s) name(s) the title of the lab the date that the lab was performed a purpose section - this is a section with no more than two sentences answering why you did this lab. a data or results section - this section should include any relevant data points and calculations obtained within the lab. Make sure you include the unknown number or letter if appropriate. a conclusion section - this section answers the question asked by the purpose any postlab questions, if any In addition, be sure to include any graphs or relevant observations. If relevant, be sure to include any averaged values, percent error, parts per thousand (ppt), etc. All labs must use the correct number of significant figures and units. Lab reports are due at the beginning of recitation one week following completion in class. Late lab reports will suffer a point penalty depending on how late they are; in other words, turn your lab reports in on time! If a lab is incomplete in terms of calculations, effort, etc., the lab will be returned to the student for completion. Make-up labs must be completed within one week of the original lab with your instructor's approval. Late lab reports must be turned in within one week of the scheduled due date, and all late labs will receive a point penalty. If you are going to be absent, you must call and leave a message on the scheduled day or your report will be considered late. Lab reports must be printed to receive credit for the assignment. If a laboratory report is ed to the instructor, a five point printing cost will be assessed to convert your lab report into a printed version. Students turning in all the scheduled labs and who have a satisfactory lab notebook will be eligible for the lab completion bonus. Failure to turn in even one lab report or keep a lab notebook will result in forfeiture of the lab completion bonus. Ask the instructor if unsure. A sample lab report example follows on the next page. Lab Safety Glasses Policy: The student bears the responsibility to bring a pair of safety goggles to each lab. At least one lab this quarter will undergo a mandatory goggle requirement. If you do not bring goggles to the mandatory goggle lab(s), a point penalty of ten points will be applied as a lab glasses rental fee. If the lab glasses are returned at the end of the period, the point penalty will be reduced to five points. Questions? Ask the instructor! Page I-x / Lab Notebooks, Lab Reports, Graphs, Parts Per Thousand

3 Page I-xi / Lab Notebooks, Lab Reports, Graphs, Parts Per Thousand A sample lab report with italicized notes from your instructor: Identification of an Unknown Metal Density Michael A. Russell Lab partner: Joyce Sherpa September 26, 2018 Purpose: Why you are performing the experiment We wish to identify the unknown density value (in grams / cm 3 ) for unknown metal sample X. We will perform multiple measurements on unknown sample X in order to determine its correct value with high precision. Data / Results: Include all information to answer the purpose Unknown metal: X Always include the unknown identifier! Include all data values collected in lab (grams, ml, temperatures, etc.) Tables are wonderful! mass (g) volume (cm 3 ) density (g/cm 3 ) trial # trial # trial # example calculation: g / cm 3 = g/cm 3 include sample calculation(s) in your lab report average density: g/cm 3 average deviation: parts per thousand: 1.1 Conclusion: Answer the question presented in the Purpose We successfully determined the density of unknown metal X to be g/cm 3. Our measurements included a high level of precision due to our parts per thousand value of 1.1. Post-Lab Questions: Complete sentences, show all calculations for full credit 1. Objects that are dipped in water will have an increase in their recorded mass. 2. An analytical scale will record masses with a greater precision than a top loading balance. 3. To find the mass of the object, subtract the empty beaker mass first g g = g Each lab report will be slightly different. Be sure to ask the instructor if you have any questions! Page I-xi / Lab Notebooks, Lab Reports, Graphs, Parts Per Thousand

4 Page I-xii / Lab Notebooks, Lab Reports, Graphs, Parts Per Thousand Graphs: Whenever you create a graph for a chemistry lab, keep the following points in mind: If creating a graph by hand, use a large portion of the graph paper to create your graph; small graphs can easily misrepresent data and/or trendlines. If using a computer program like Microsoft Excel, use large graph sizes when creating lab reports (up to the size of one complete page.) Plan ahead! Make sure all the data points will fit on the graph but will not be too crowded together horizontally or vertically. Again, use as much of the graph paper as possible when constructing your graph. On the vertical axis, label the quantity that is being plotted (i.e. "Time") and put its units in parentheses (i.e. "(seconds)". Do the same on the horizontal axis. If you are drawing a best-fit line through the data points, do not connect the dots! Instead, draw a line which has some data points on each side of the line you are drawing... think of your line as an "average" of the data points. Never force a graph to go through the origin (i.e. at x=0 and y=0) unless expressly told to do so. Examine your graph: are there one or two points which are farther away from the line than the other points? If so, make sure you plotted them correctly. Use regression techniques to find the equation for the best fit for your data. ALWAYS include the regression equation with the graph itself. Linear regression equations should always be accompanied by the correlation coefficient, r, and not just R 2. To find r from R 2, take the square root of R 2. If the slope is negative, your r value will be negative as well. An example graph follows: Page I-xii / Lab Notebooks, Lab Reports, Graphs, Parts Per Thousand

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7 Page I-xv / Lab Notebooks, Lab Reports, Graphs, Parts Per Thousand Periodic table from ScienceNotes.org Page I-xv / Lab Notebooks, Lab Reports, Graphs, Parts Per Thousand

8 Page I-xvi / Lab Notebooks, Lab Reports, Graphs, Parts Per Thousand Parts per Thousand (ppt) Guide Parts per thousand (ppt), also known as the relative standard deviation, is useful when comparing the uncertainty between different measurements of varying magnitude (i.e. it is a measure of the precision within an experiment.) Parts per thousand can be applied to any set of data where more than one experimental value has been applied i.e. volumes, percentages, concentrations, etc. We will use parts per thousand often this year, so knowledge of how it works is critical for the successful student. For the values x 1, x 2 and x 3 : Take the average of the values average = Find the deviation of each value relative to the average Find the average deviation of the deviations sum x 1 + x 2 + x 3 # of values = 3 deviation 1 = absolute value (average x 1 ) = average x 1 deviation 2 = average x 2 deviation 3 = average x 3 average deviation = sum of deviations # of values = deviation 1 + deviation 2 + deviation 3 3 Calculate the parts per thousand (ppt) for the values ppt = average deviation average * 1000 Example: Calculate the parts per thousand for the values 35.72%, 35.92% and 36.02% Average = 3 = % Deviation 1 = = 0.17 Deviation 2 = = 0.03 Deviation 3 = = average deviation = = 0.11 % parts per thousand = *1000 = 3.1 unitless Parts per thousand relates the deviation to the magnitude of the experimental data. Consider these two sets of data each with an average deviation of ±0.010: Data set 1: ± 0.010, ppt = (0.010/0.250) x 1000 = 40 ppt (not very good precision). Data set 2: 4.50 ± 0.010, ppt = (0.010/4.50) x 1000 = 2 ppt (excellent precision) Although both scenarios have the same deviation, the relative deviation compared to the data gives very different results. Patience and focus is a virtue in this lab. Page I-xvi / Lab Notebooks, Lab Reports, Graphs, Parts Per Thousand