Ms. Grobsky’s Guidelines for the AP Chemistry Lab Notebook One of the major goals of science is to be able to clearly and accurately describe results of experimentation and research. In order to achieve this goal, you will keep an accurate, chronological notebook of all lab work, using a scientific format. A lab notebook will be used to explain laboratory procedures, record ALL lab data, record observations, show how calculations are made, discuss the results of an experiment, and explain the theories involved. A record of your lab work serves to form an important document that will show the quality of the lab work that you have performed. You may need to show your notebook to the Chemistry Department at a college or university in order to obtain credit for the laboratory part of your Advanced Placement Chemistry course. As you record information in your notebook, keep in mind that someone who is unfamiliar with your work may be using this notebook to evaluate your laboratory experience in chemistry. When you explain your work, list your data, calculate values and answer questions, and be sure that the meaning will be obvious to anyone who reads your notebook. A laboratory notebook is not meant to be a formal lab report, but a concise summary of experimentation performed. For this course, please follow these guidelines. GETTING STARTED: GENERAL NOTEBOOK SETUP •
Use a bound notebook (so pages cannot be torn out). •
Number all pages on the upper right hand corner in ink. The organized and neatly written lab goes on the right-­‐hand side of each page. The left-­‐hand side is for scrap and preliminary calculations. •
Leave two pages (pgs. 1 and 2) for your Table of Contents, which should include experiment titles and corresponding page numbers as they are performed. Leave one page (pg. 3) for your “Contact List”; names, emails, phone numbers of lab partners go here. •
All pages must be numbered and dated. When you begin writing on a new page, record the date in the upper right corner below the page number. •
Ink may only be used; no whiteout. Use permanent blue or black ink for all entries. Think about a reasonable layout for your data (a table perhaps) before putting pen to paper. Get in the habit of writing everything in your lab notebook (no scraps of paper to lose). Do not erase, scribble-­‐over, or whiteout anything; simply cross out errors with one line so they are still legible (e.g. 0.503 g 0.530 g). You WILL get better at this. READY TO BEGIN: THE NOTEBOOK FORMAT (* to be completed before lab is performed) •
TITLE/PARTNER NAME* The title should be descriptive; the title on your lab handout may not suffice. •
INTRODUCTION/PURPOSE* In a sentence or two, describe the reasons or objectives for completing the lab. Use your own words; do not paraphrase the lab manual writeup. Why are you doing this lab? What are you trying to find out? In another sentence or two, explain how you will accomplish your task. Details such as “I will add 3 mL of HCl to 2.0 g zinc” are inappropriate. A statement such as “I will dissolve the metal sample in concentrated HCl…” followed by a balanced equation, is appropriate. •
PRE-­‐LAB QUESTIONS* If the lab handout has specific pre-­‐lab questions, thoughtfully answer them in this section. •
PROCEDURE Briefly summarize the procedure to be followed; use a flow chart, or outline, and/or drawings. If you number the steps, you will be able to refer to them later in the Observations section. You do NOT need to write out the procedure in complete sentences and do NOT copy directly from the lab manual. The first time you do an unfamiliar technique, include a description of how to assemble or operate any apparatus. Write the procedure with enough detail that a trained chemist could reproduce your results from what you wrote (for example, be sure to include elapsed times, instrument name, solution concentration, colorimeter wavelength, voltage, etc.). You may use an outline or bullet points. •
DATA Record the data during the experiment; do not record on scraps of paper for later transferal into your notebook. Be sure to use the correct number of significant digits; this will eliminate the need to specify exactly what dispensing device (eg. graduated cylinder vs. volumetric pipette) you used. Be sure to record actual measurements—for example, initial and final burette readings, starting and ending time, not the difference done in your head. Use data tables when appropriate; simple calculations may be included in the data table. Be sure to label all tables with a title; “Data Table” is fine, or “Data Table II” if there is more than one. •
OBSERVATIONS Report any observable occurrences (color change, precipitate, gas evolution, heat generation, etc.). •
CALCULATIONS Include all pertinent calculations. For all calculations, express the equations in words first before showing the numbers used in the equation, or label each line. For example: concentration of substance = mass of (substance + beaker) – (mass of beaker/molar mass/volume of solution) = x.x M. Do NOT show calculations of molar mass (e.g. H2O = (2×1.01) + 16.00) unless it is an intrinsic part of the experiment. Show work for calculations and express all answers to the correct number of sig figs and include units. For repetitive problems, provide one sample calculation. o Summarize calculations in a table when appropriate. Be sure to label all tables. •
GRAPHS Make graphs an appropriate size so they are clearly legible; all graphs must have a descriptive title. Typically you will show a best-­‐fit line or curve; oftentimes, you will need to calculate the equation of the best-­‐fit line. You may draw graphs by hand or paste in a computer-­‐generated graph. Be sure to label all axes with appropriate labels and units! •
CONCLUSIONS This is where you interpret the data you obtained. What do the calculations/ observations/graphs reveal? What theory was demonstrated? Compare your results with accepted values, or with the class values, and list percent error when applicable. State whether your results were too high or too low. Suggest sources of error that would have caused these experimental results. Hypothesize why the errors occurred and what might be changed to avoid these errors. Random error exists in all measurements and should NOT be mentioned. Human error (e.g. spills) and mistakes in recording data are NOT the same as experimental error; usually, they are addressed by repeating the experiment. •
ANSWERS TO LAB QUESTIONS Rewrite the analysis/conclusion questions from the lab sheet and answer each question. LABORATORY NOTEBOOK RUBRIC •
AP Chemistry labs are chosen to aid your understanding of chemical principles, practice manipulation of some typical lab apparatus, and teach you about scientific problem solving. Getting the “right answer” is much less important than understanding why an experimental result is questionable. •
Discussion with your lab partner is expected. However, everything should be in your own words, especially the Introduction/Purpose and Conclusions. •
Lab notebooks will be collected approximately every third lab. These will be graded out of 35 points. Please see Figure 1 for the rubric that states specific grading guidelines. FIGURE 1-­‐LABORATORY NOTEBOOK RUBRIC 5-­‐4 Exceeds Standard 4-­‐3 Meets Standard 3-­‐2 Approaches Standard 2-­‐1 Does Not Meet Standard Introduction/Purpose Lab objectives clearly stated with rationale. Lab objectives clearly stated. Lab objectives clearly stated. Lab objectives not clearly stated. Procedure is missing information. Procedure is missing essential information; not reproducible. Graphs and/or data tables have missing or incorrect units and/or labels. Data is missing and/or graphs do not include all trials. Calculations are complete but contain minor math errors. Calculations are incomplete and/or contain significant math errors. Procedure Data/ Graphs Calculations/Results Conclusion Formal Lab Questions Statistics/ Error Procedure is not Procedure is copied from lab reproducible, but manual and is in resembles formal form of flowcart, written illustration, etc. procedure. All data is presented All data is in tables with correct presented in units & sig. fig. tables with Graphs have titles & correct units. labeled axes; lines for Graphs have all trials are labeled titles & labeled with annotated text axes and include when appropriate. lines for all trials. Calculations are Calculations are accurate & accurate, & include include formulas formulas used, units, used. Results for sig. fig. Results for all all trials are trials are provided in provided in an an organized table. organized table. Conclusion Conclusion answers answers question(s) & question(s) & provides supporting provides data. supporting data. Answers to questions are accurate, clearly explained, and well supported by data. Demonstrates thorough knowledge of applicable chemistry concepts. Answers to questions are accurate & demonstrate knowledge of applicable chemistry concepts. Conclusion Conclusion does not answers answer question or question(s) but does not provide does not provide supporting data. supporting data. Answers to questions contain minor Answers to errors, but questions are demonstrate incomplete and/or knowledge of contain significant applicable errors. chemistry concepts. % error/std. dev. are % error/std. dev. % error/std. dev. calculated accurately. are calculated calculations Sources of error are accurately. contain minor valid & accurately Sources of error errors. Sources account for high or are valid for of error are not low values in both individual & class well supported individual & class results. by results. results. % error/std. dev. calculations are missing or sources of error are not consistent with results.