JoVE Lab Manual
Lab: Chimica
Lab: Chimica
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Cura corretta dei quaderni di laboratorio
One essential aspect of working in the laboratory is maintaining an accurate and updated record of the experiment using a lab notebook. The lab notebook is essential in both academia and in industry, as it not only provides you with a record of exactly what was performed, but it also serves as a legal document that proves ownership and originality of research.
It is essential that you use a bound carbonless notebook so that the copy can be removed and submitted to the instructor. You must always write in pen, never in pencil. Prior to starting the experiment, you must generate a pre-lab report in your lab notebook.
To do this, you must first read the procedure thoroughly and determine the objective of the experiment. Then, you'll write down all of the background information needed to understand the experiment and protocol.
Next, you must write the procedure steps while including clarification of complicated steps and calculations of values you may need. Simply copying the protocol will not suffice. Creating a flow chart may be necessary to help you.
You will also write out all balanced chemical reactions and determine theoretical yields in advance and identify the physical properties of all materials that you will use. Possibly the most important step is to identify the safety risks of all reactants, products, and solvents used. These hazards must be obtained from the Material Safety Data Sheet, or MSDS, for each substance.
When you are prepared to run the experiment, you will first write down the date and the lab experiment being done. Then, record all steps as they are performed and include exact measurements, such as volume, temperature, and weight. Always keep your notebook close by and record information immediately. Never scratch notes on paper towels or scrap paper.
If a mistake is made, it should be crossed out using a single line and the correct information written immediately. Be sure to always include any relevant observations, like a temperature change, color change, or pH change. Always include all observations and data points, even outliers and failed experiments. Never remove pages or data points in an attempt to hide mistakes.
When you are finished with the experiment and finished with your record-keeping, cross out the unused portion of the last page and then sign and date all pages. In this lab, you will practice notebook-keeping skills by performing the nitration of methyl benzoate. It is essential that you maintain an accurate and thorough record of your experiment in order to properly analyze your results when finished.
Cura corretta dei quaderni di laboratorio
Organic Lab Notebook Keeping
Record keeping is a vital skill in science and organic chemistry labs. Without proper notes, descriptions, quantities, or observations, an experiment conducted in the lab cannot be replicated or reproduced. Therefore, keeping an accurate and up-to-date notebook is necessary to achieve reproducibility in science. A laboratory notebook is a powerful tool in both academic and industrial settings. It becomes especially important when a discovery is patented and commercialized. In this instance, the lab notebook is a legal document that proves ownership of an idea, process, substance, or technique.
The critical information in a lab notebook includes the steps that were performed and all observations. The experimental objective must be clear and well-written so that it is easily understood. For each experiment, several essential sections are recorded in the lab notebook. A lab report consists of a pre-lab, lab protocol, observations and results, and post-lab.
A bound lab notebook with no loose pages is preferred. Pages must not be able to be torn out easily, as this compromises the validity of the records in the notebook. For laboratory classes in which you will be graded, a notebook that contains self-duplicating sheets should be used. This allows both you and your instructor to have a copy of your laboratory notebook pages.
Complete all record keeping in pen. Any writing implement that can be easily erased is not acceptable. All notes must be permanent because this ensures the validity of the records in the notebook. All notes, observations, changes to the procedure, and data collected must be written directly in the lab notebook. Never write notes on loose paper or scribble out records in your lab notebook. If there was a mistake or a change was made to a record in the notebook, neatly cross out the error with a single line and write the correction next to it. Scribbled out notes or ripped out pages invalidate your record-keeping and counters the primary purpose of accurate record keeping. When all record-keeping is complete, the blank portion of the remaining page should be crossed out. All pages used must be signed and dated.
Pre-lab
The pre-lab must be completed before the experiment. To write the pre-lab, read the procedure thoroughly, research the background of the experiment, and title the experiment with a descriptive phrase. For example, “Synthesis of 1,3-pentanediol” is a better title than “Experiment 1”. Include the date that the experimental procedure was performed, your name, and your lab partner’s name, if necessary. It must also include the objective of the experiment, which lists the goals. Next, write all balanced chemical reactions that will occur in the experiment. List any relevant properties of the chemicals used or produced during the experiment in a tabular format, such as melting points, molecular weights, and densities. Carry out any necessary calculations before the actual experiment.
Additionally, identify the safety risks of all reagents. These are included in the material safety data sheets (MSDS), which are provided by the manufacturer. It is also important to calculate the theoretical yield of the product. This will help you understand if your experiment is proceeding correctly. Finally, write the step-by-step procedure in your notebook. This should be written with enough descriptive information so that someone else is able to reproduce your experiment. As such, this should not be a word-for-word copy of a procedure from a different source. It must be written in your own words.
Lab Observations
This section contains all observations and results from the experimental procedure, so it must be filled out concurrently with the experiment. Here, you’ll record any relevant observations, such as the temperature of the reaction and any changes in color or pH as the experiment proceeds. This is where the exact mass of reactants and products are recorded. Also, make sure to write down the names of any computer files generated during the experiment.
Post-lab
The post-lab report presents the data and final analysis. The post-lab includes your hypothesis or expectations compared to the experimental results. If the expectations differed from the observations, this should be discussed, including possible explanations as to what caused the differences. The limitations of the technique, as well as any improvements that could be made to obtain better results, should be discussed. Finally, the post-lab report should summarize the experimental data and provide a clear conclusion with an explanation of any errors.
References
- Harris, D.C. (2015). Quantitative Chemical Analysis. New York, NY: W.H. Freeman and Company.
