WordPress.com



What makes a good lab Report?(Do not say I, we, or me)Introduction: (not needed unless requested)This section should contain an introduction to what will be focused on in the lab. This is not the place to talk about procedure. Any theories or relationships you are making use of should be introduced at this point formula/algorithms etc. Example: This lab introduces students to the idea of using stoichiometric relationships to calculate the theoretical yield of a single displacement reaction. The concept of limiting reagents is also explored as the lab required students to measure and mix the reactants chemicals on their own. The students also gain experience with filtration techniques and determining the percentage yield of their reaction at the end of the experiment.Materials/Apparatus: (see lab sheet unless otherwise stated)This section should contain a listing of all the materials that are required to conduct the lab. If someone were to collect all the items you list in this section they should be ready to conduct the lab in the same way you did. If there are any special pieces of equipment which had to be set up in a specific way, this should also be noted in this section. Example: 250 mL beakerCopper (II) chlorideFunnel Glass stir rodElectronic balanceFilter paperIron nails Ring standThe filtration apparatus was constructed from the ring stand, funnel, and filter paper in the following fashion (sketch/picture)center7620000Procedure: (see lab sheet unless you make your own procedure)Here we list the procedural steps taken to complete the lab. Care should be taken to ensure the steps are clear and manageable. Don’t try to do too much in a single step. The sequence should follow the natural progression of the experiment. Use numbering to identify when a new step is taking place. Waiting times and specific temperature/mass/volumes should be stated explicitly. The rule of thumb is to have a reasonable account of how a person of similar experience and skill could do exactly what you did.Example: 1. Weigh 5.00 g of copper (II) chloride on a balance and place it in a 250 mL beaker.2. Add about 150 mL of water to the beaker and ensure all the copper (II) chloride dissolves.3. Weigh two iron nails and record their mass.3. Place the nails in the copper (II) chloride solution. Ensure they are completely covered with solution. Add more water if necessary.4. Let the nails sit for 24 hours.5. Filter your product to collect the copper which has formed.6. Wash the copper product and let it dry for 24 hours.7. Weight and record your final mass of product.Data: (Always required in a lab report)This section of the report is very important. This is where you present the data you collected to the reader. Only data is presented in this section. Not calculated values! It should be presented clearly, a table is the standard expectation in the scientific community. There should be titles and identifying labels. It is not acceptable to present data in a confusing way, or in such poor quality that it may not be discerned accurately by the viewer. Measurement uncertainties should be reported and the data should be in agreement with the uncertainty.Example of bad data presentation:SubstanceMass with associated uncertaintyNails9.46 +/- 0.001CuCl25.111 +/- 0.001Metal4.02 +/- 0.001Paper.42 +/- 0.001*There is ambiguity in the substances and the uncertainty does not align with the data. Also, the mass unit is unknown to the reader. Expecting assumptions to be made is poor data presentationExample of quality data presentation:Data tableSubstanceMass (in grams) with associated uncertaintyIron nails (Fe)9.460 +/- 0.001CuCl25.111 +/- 0.001Copper metal (Cu)4.020 +/- 0.001Filter paper0.420 +/- 0.001This data is listed in a much clearer way. It is much clearer what substances are being used and the measurement units have been identified. The measurement uncertainty is reported for each measurement. There is alignment between the uncertainty and the decimals reported in the measurement.Qualitative Observations: This section is required in IB formal labs. These are not measurements. Measurements would go in the data section of the report. This is a section for things you observe which could/will be meaningful in the discussion portion of the lab report.Examples: bubbling, color change, smell, changes in the reaction solution, patterns of behavior, etc.Calculations: (always required if relevant to the lab)The calculations need to be shown for lab reports. This is how you should the readers how you used the data. To ensure honesty and good scientific practice we must show this process to the reader. Since most of our reports are for learning purposes, the expectation is that one full calculation is shown from start to finish. This lets the reader see a full procedural calculation for one complete trial of the experiment. If you have conducted the same set of calculations for other trials you do not need to show all of those calculations. (But you do need to do them somewhere)Examples include:Mole calculations, conversion calculations, taking the difference between two masses, etc.If there is a formula, this is where you would show it being used.Results/discussion:-Talking about what happened- referring to the results that you found.-discussing any errors that may have affected your results-Are your results in agreement with what might be expected?-Using accepted ideas/theories to support your own findings.-Why did you get the results you got?- Do not use personal pronouns.The discussion component of the lab report should not include personal pronouns. Writing should be kept to third person. This is done in respect of the fact that anyone should be able to conduct the experiment in the same way. At this point in a report, we want to state the result of the experiment (what was found). It is highly appropriate to discuss how your own value compares to a true or accepted value (if you have something to compare to). If the value you find is not in agreement with the accepted value we need to discuss sources of error. Random errors are always present but it is systematic errors that we need to work hard to identify. The systematic errors can potentially be eliminated if we can identify where they are taking place. (We can suggest how the error could be addressed even if we don’t have the ability with our equipment to fix it)In the near future, we will learn how to compare the experimental error to the measurement error to determine which contributes most to the error.Example of poor discussion:The experiment was conducted and the mass of copper was found. The final mass of copper was less than expected. Some reasons for losing copper might be that it spilled out of the beaker when the water was being drained off. There was also some copper left in the beaker that could not be collected. This would explain why there is less copper than expected. It is also possible that some of the copper made it through the filter paper and was lost in the waste beaker.Example of good discussion:In this experiment the final mass of copper product was found to be 4.020 g. This is less than the theoretical yield of 5.275 g predicted by stoichiometry. A 76.21% yield seems acceptable for this reaction. The experiment took place in three separate stages over a period of one week. Although this slow reaction likely had time to reach completion, there was also time for other competitive reaction to take place. Oxidation of the nails by oxygen could also have taken place after the intended reaction had completed. Trace amounts of copper were observed remaining in the beaker after filtration. This would also account for the yield being less than the theoretical value. Conclusion: (State what you have found)Typically you want to look back and address the purpose of the experiment in this section.This is the last section of a lab report. As a result, it is critical to state what you found. Often it feels like a repeat of what we said earlier in the report (it often is a repeat). Just like you repeat your point at the end of an essay, you restate what you have found in this section of the report. You can state the values for your errors (usually reported as % error). The nature of the experiment will typically guide you in determining what other information should be included in this section.Example: The mass of copper product collected in this experiment was 4.020 g. The percentage yield was found to be 83.4%. The discrepancy in the yield can be explained by multiple factors such as the extent to which the reaction reached completion. The color of the solution suggested there were still reactants which had not reacted (you would need to have recorded observations to say this). Also, loss of the product during collection was an issue. ................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download