If the experiment is preparative experiment, the introduction also includes the balanced equation for the reaction. In organic chem.., there are different types of experiments: technique and preparative. A technique experiment is one in which you are performing a technique for the first time and studying its details, for example, distillation and extraction. A preparative experiment is one in which a compound is synthesized from other reagents. Physical Data List the molecular weight, melting point, boiling point, density, solubility, and hazards of all pertinent chemicals used in the experiment.
You can find this information in the CAR Handbook of Chemistry and Physics. (We have this book at school, and a CD-ROOM version as well. ) Or, you can find the information on the Internet (see: Hazard and Physical Data for Compounds page). Cindered. Com is an excellent site to find this data. The physical data are most conveniently presented in tabular form, although in a preparative experiment you may put the amounts of reactants and products under the balanced equations for the reaction.
Calculate the amounts of reactants (or compounds to be purified) in oleos and grams or ml (as applicable). In a preparative experiment, calculate the limiting reagent and the theoretical yield of the product. Be sure to include your calculations for these values. Procedure Briefly summarize the procedure to be followed, preferably either as an outline or as a flow chart. You do not need to write out the procedure in complete sentences and do not copy directly from the Lab Manual. All you need is a brief but complete listing of what you plan to do in the lab.
The first time you do a technique, such as distillation, include in the procedure section description of how to assemble the apparatus and how to conduct the distillation. In later experiments, it will be sufficient to state only that the liquid was distilled. Data and Observations Your observations of the experiment as it progresses is important, new information. Write these observations (color changes, appearance of crystals, formation of an emulsion, boiling temperatures, test results, etc. ) in your notebook as you do the experiment.
Also record the weights of reagents and products and tare weights in this section. In general, you do not need to re- rite the Procedure section in these observations, instead, you may state that “the procedure was carried out as planned” or “the procedure was carried out as planned except At times, however, you may have to write the procedure out partially. For instance, if you state ‘the solution turned green,” you will have to write out enough of the procedure so that your instructor will know at what step in the reaction the solution turned green.
As a guideline, consider that from the procedure and data and observations sections, any chemist should be able to duplicate your experiment. With this in mind, be thorough but include only pertinent information. Discussion of Results This is the section in which you interpret the data obtained in the previous section. For instance, indicate the amount of purified compound that you obtained and how the purity and identity of the compound was assessed. In a preparative experiment, state the percent yield. Include and discuss instrument printouts, such as GO traces and IR spectra (if you have them).