Chem 120, Long

LAB NOTEB OOKS A ND R EPOR TS Setting up the Lab Notebook: 1. A bound duplicate page notebook is essential. 2. Save the first page of the notebook for a Table of Contents. Save space on the inside front cover for a Spelling List of words that give you problems. 3. If pages are not already numbered, number all pages. 4. Use a waterproof nonerasable ink pen which will produce a good duplicate copy. 5. Start each new Experiment on a new page in the lab notebook.

The Prelab Writeup: In general: 1. Prelabs are due before the beginning of lab to give me a chance to look at your work. 2. Prelab work may be done in pencil, ink, or on a computer. Prelab questions do not have to be in the lab notebook. Content: There may be written questions for the Prelab. In addition, the first few sections of the lab report are written: 1. Title of experiment and reference source The title should be descriptive, not just an experiment number. (Example: "Expt. 22 - Ka Determination", not Expt. 22). List the book or state that the experiment came from a handout. 2.Purpose and Overview of experiment (write this heading for this section) a. The Purpose and Overview section is intended to present clearly to anyone with a chemistry background, a brief summary of what you plan to accomplish and calculate in the experiment, with what major chemicals and equipment, and (in a general way) how. It describes the goals and design of the experiment without getting into procedural or mathematical details. The goal you state should NOT be a general educational objective such as "to learn how to use the pH meter" (although, of course, there are educational objectives). The overview should NOT be a list of all the procedure's quantities and steps. For example: "In this experiment the goal is to determine the ionization constant of a known weak acid, acetic acid, by titration with standard sodium hydroxide. A pH meter will be used to follow the titration and a titration curve will be plotted. The ionization constant will be calculated from the pH at 4 points along the titration curve using the equation for the equilibrium constant expression for Ka." Sometimes an experiment has several parts or several purposes so there will be more than one purpose statement. Sometimes an experiment involves many short experiments with different chemicals and procedures. In these cases a general statement, as specific as possible, can be given in the Purpose/Overview section with the list of actual chemicals in the Data Table. For example, "The purpose of this experiment is to identify which of the pairs of ionic

2 compounds listed in the Data Table react when mixed and to write net ionic equations for those that do." b. If an experiment involves a chemical reaction, the balanced chemical equation should be included. c. The Purpose/Overview section should also include any "rules of the game". Examples include: - "The experiment will be done twice and the results averaged." - "No procedure is given. An outline of my planned procedure is given below." d. If different people in the lab are using different compounds or methods, state which one you will be using. 3. Any changes from the reference source procedure If you are told to modify the book or handout’s procedure in any way, briefly describe the modifications. Include a sketch of any apparatus set-up to be used which was not in the reference or was different than in the reference. If the procedure is to be of your own design, outline your planned procedure. 4. Procedure, Observations, and Data If several data items will need to be collected, set up a labeled organized blank Data Table. Include places for any unknown numbers, exact mass of compounds used, exact molarity of solutions you used, etc., even when amounts are specified in the procedure. Leave lots of white space. If you will need to use data from tables in the lab handout or other sources to determine your experimental result, also include that data and state your reference source. If a Data Table will be generated by the lab computer, list headings for the columns of data. Procedural information may be entered into the lab notebook or outlined on separate paper before lab to help you avoid confusion in lab (you can even do it in pictures) but is not required. If written in the lab notebook, leave lots of space to add notes in lab.

Data Entry During Lab: In general: 1. All data and observations obtained during a lab experiment must be entered directly into the lab book in ink during the lab. No pieces of scrap paper should ever be used. Don’t be afraid to write in the book, you can recopy and reorganize any messy sections when you put together your lab report to turn in (see Lab Reports below). 2. Put your name and the date at the beginning of each day's entries. If the data collection is on more than one page, date each page. 3. Keep it as neat and clear as possible (although we know it won't be perfect). Someone else should be able to read this and find things. These guidelines may help: - Enter necessary data into organized, labeled Data Tables even if you have already mentioned it in the procedure description. - In general, leave lots of white space, with more space between sections. - Any errors are to be deleted with a single line and the correct entry written clearly nearby. Do not try to change numbers by writing over them darker. - Don't start making entries diagonally or sideways on the page.

3 - Enter data in the order you do it. When you get to the bottom of the page go to the next one (or say “continued on page ___”) instead of writing in some corner of the page above to save paper. 5. At the end of the lab each day, check that all relevant procedural notes, observations, and data have been entered. Then, before leaving the lab, get the instructor to sign the lab notebook to verify that the material was written during the lab period. Bring the lab notebook to the instructor before you start cleaning up to give her time to sign them all so you won’t have to wait to get your book back before leaving. Calculations from the data normally do not need to be signed. Information entered in the lab notebook should include: 1. Procedure and Observations. You should write out everything you do and observe as you do it. The procedure should be exactly what you did and saw, not just what the directions said to do and see. Your procedure and observations may be in abbreviated form or like a story about your day in the lab (the parts relevant to the experiment!). For example, the book procedure may say "For the first heating, heat for 10 minutes without letting the crucible get red hot. The contents should turn white. Weigh." You heated for 10 minutes, then looked, and only half the contents were white so you heated for another 10 minutes. The above might be written (in abbreviated form) as: "First heating: - heated 10 minutes without crucible getting red hot - contents were only about half white so didn't weigh - heated another 10 minutes without crucible getting red hot - contents were completely white - weighed (10.6754 g)" 2. Data. All unknown numbers, raw data, etc., with appropriate units should be entered in an organized way so that it is clear which specific part of the experiment it relates to and what substance was measured. Measured numbers must be reported to the proper number of significant figures. Numbers calculated from data are not to be included in Data Tables unless they are obtained by simple subtraction (such as weight of sample obtained by subtracting the weight of the crucible from the weight of the crucible + sample). Most “Data” Tables printed in general chemistry lab experiment directions are not really data tables. They are data and calculation and result summary tables. I want you to know the difference and keep these types of things separate. 3. Calculations from the data. It is recommended, but not required, that calculations be done in the lab notebook. This keeps all your work on the experiment in one place so you won’t lose it. Remember, the lab notebook is not necessarily your final report. If you make a mistake, you can cross it out with a single line (or cross out the whole section with an X).

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“Complete” Reports for Lab Experiments: In general: 1. Must be neat and organized (or may be returned for rewriting with points deducted). Present it as though the reader knows chemistry but doesn’t already know what you did. Label sections with headings and assemble them in order. 2. Must be on time (points deducted for late reports). 3. Must be on separate paper, not in the lab book. One copy of the lab notebook pages containing the original data will be attached. 4. Must be typed but calculations may be written by hand to save time. Sections in a “Complete” Lab Report: Note: Some lab reports will be fill-in forms and not “Complete” reports. But of those where a complete report is specified, most will follow this format. Modifications of this format may be suggested for some experiments to make the report more readable. At the top :

Your name and section Partner’s name (if it is an experiment done with a partner) 1. Title of Experiment and Reference Source 2. Purpose and Overview 3. Any changes from reference procedure 4. Procedure, Observations, and Data 5. Calculations or other data manipulations 6. Evaluation and Comments on Results 7. Summary of Experimental Results and Conclusions 8. Answers to any Assigned Questions 9. Signed data Entry pages from lab notebook) - if not included above as part of report

Description of what is expected in each section: 1-3. These parts were completed as the Prelab write-up (see description there). Retype them here, rewriting if necessary. Prelab questions do not have to be included unless they involve calculations needed for the experiment or design of procedures. 4. Procedure, Observations, and Data. Organize this into neat data tables wherever possible. The procedure should be abbreviated, it may even only be headings. You should not waste the time copying the whole procedure from the lab manual. 5. Calculations. Present your organized calculations, explaining your reasoning. - Headings for each calculation setup are often sufficient to explain simple calculation steps (For example: "Use PV=nRT to calculate P") - If reaction equations are needed for the calculation, show them. - If you are doing multiple calculations of the same type (calculations from three titration trials, for example), you may explain it once carefully labeled, then show all the calculation set-ups with just numbers. Don’t just do it in the calculator. If you have arithmetic or data copying errors

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5 and your calculations are together and labeled as to what you are calculating, it will be easier for you to spot those errors and fix them and I can give you credit for doing the calculation correctly if there is a math mistake. - Be sure to report answers to the appropriate number of significant figures. Evaluation or Comments on Results a. This is the section where you comment on what you expected and why and whether your results agree with what was expected or not. It is not a discussion of whether the experiment was hard or you liked it. When numerical results are obtained from an experiment, evaluation of accuracy and/or precision are done here if the appropriate information is available. b. If experimental results are different from the actual values, or from what is reasonable, you should suggest reasons for the results being off in the direction they were off. These comments should include as much evidence as possible, based on your observations during the experiment. Be specific, not “experimental error” or "the experiment was hard and should have been repeated". State what should have been done differently. The kinds of comments here vary considerably with the type of the experiment. In many experiments you will be told what types of things to comment on. Summary of Experimental Results and Conclusions. a. Your experimental results should be summarized in a neat table. Include any unknown numbers or other identifying information, all the results you sought in the experiment, actual values if known, and % error values where determinable. For example: Liquid Unknown #456 Exptl. Density Trial 1 = 3.251 g/mL Exptl. Density Trial 2 = 3.259 g/mL Average Exptl. Density = 3.255 g/mL Precision Error = 0.2% Actual Density of #456 = 3.259 g/mL Experimental Error = 0.1% b. Anything which was asked of the experiment as part of the Purpose should also be resolved here as a Conclusion. For example if the Purpose of the experiment was to determine if compound A was a better oxidizing agent than compound B, then you should have a Conclusion statement about which was better. If there are many related conclusions, a table might be the best way to present them. For some experiments, for example where the whole purpose is to determine the numerical value of the density of an unknown, the Results table is all that is needed since that is the Conclusion. Questions. Answer any assigned Questions. Data Entry pages from lab notebook. These are the pages in your lab notebook where you entered the data and procedures while doing the experiment (calculation pages not needed). Attach one copy of these signed pages. Karen Long last revised F2010