Examples of Lab Report Conclusions
What grade would you give each conclusion? What is wrong with each conclusion? How could each conclusion be improved?
Conclusion #1: ______out of 3
What’s wrong? ______
Improve? ______
As described in the lab manual: 1. Record the barometric pressure. 2. Measure about 10 g of ice using the chemical balance and place it into a 100 mL beaker. Heat over a flame until half of the ice has melted. Remove from heat and measure the temperature as accurately as possible using your laboritory thermometer. Repeat with a 10.0 g sample of your unknown. Be sure to record your unknown number. 3. Measure 50 mLof water using your graduated cylindar and pour it into a 200 mL beaker. Bring the liquid to a boil over a flame. After the liquid has been boiling for approximately 1-2 minutes, measure the temperature of the boiling liquid. Repeat with a 10 g sample of your unknown. Record all data in your lab notebook and clean up. We followed all the steps above pretty much closely and pretty much got the results for water that we expected, except that the stockroom had cheap thermometers because one of them broke (this was my lab partner’s fault – she used it as a stirring rod which is exactly what you said not to do in your lecture) and the new one was off by a few degrees – but it was close enough for this simple experiment. The pressure in the room was 761.2 and the temperatures we measured for our unknown were: -15 and 17. Correcting for our water results this made our measurements –15.2 and 17.4 after the corrections. Based on these temperatures and the data we looked up in the library, our unknown was certainly “blabber gas.” The error in our results was really small and the experiment worked really good. Other errors include: possible math errors in our calculations and human error. Overall the lab was really good and we learned quite a lot of stuff. I especially liked the part where the blabber gas exploded when heated scaring my partner (I think that may be why she broke the thermometer). The only criticism of the lab is that the equiptment wasn’t really great and that we ran out of time but otherwise it was a really good experinence and I think it taught us a lot of chemistry.
Conclusion #2: ______out of 3
What’s wrong? ______
Improve? ______
This lab investigated how the magnitude of vibrations affects the amplitude of a seismograph. In order to study the problem we created three magnitudes of movement and measured the amplitude of each with a seismograph.
My results showed the trial with the greatest amplitude was trial three because the table was being hit with the most force, making the table and the pen move more than the other three trials. The trial with the least amplitude was trial two because the table was hit with the least amount of pressure. While observing the experiment, I noticed that the more vibrations or higher magnitude resulted in a higher amplitude on the seismograph. The harder the table was being hit, the higher the amplitude rose.
This proves my hypothesis was correct. I believe the results are accurate because while the experiment was in progress, the frame moved at the same rate as the table. It was proven in trials one through three that the increased magnitude of table movement caused the greatest amplitude differences on the seismograph. It is clear, therefore, that the movement of the frame also corresponds to the amplitude of the seismograph. The bar and marker shared the same relationship with the table and the frame. The more the frame moved, the greater the amplitude on the seismograph.In order to further investigate this problem, next time I would try the experiment on a different surface and would add additional movements of varying forces for further readings on the seismograph.
Conclusion #3: ______out of 3
What’s wrong? ______
Improve? ______
Based on the measurement data, the difference between accuracy andprecision is evident. The average length obtained from both rulers could be written to3 significant digits based on the calculated uncertainty of 0.05 cm. Yet, the averagevalues 8.23 cm and 8.83 cm for the special ruler and plastic ruler respectively did notagree. Precision, which is determined by the number of significant digits wasidentical for both rulers. However, which average value was correct or accurate,could not be established.The most uncertain measurement was the flame measurement at +/- 1 cm. In thecase of the flame it was not the instrument but the object, the flame itself, whichcaused the high variation.
Conclusion #4: ______out of 3
What’s wrong? ______
Improve? ______
In this experiment we figured out how to find the density of metals. We found all three densities easily. We had some error because of measuring. I learned a lot from this lab.
Which one of the ones above do you feel is a good example for how conclusions should be written? ______