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Galvanized Nails, Quality Control, and an Introduction to Green Chemistry

# Before the lab was over each student was required to

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Before the lab was over, each student was required to enter in their initial and final masses of each nail so that the GTF could calculate the mean and deviation of the mass lost, percent of mass lost and mass lost per mm 2 . Table 2: Class Data Mass Zinc Lost(g) % Mass Lost(%) Mass Lost(g)/mm 2 Average 0.10g 11.5 0.00045 Deviation 0.04 3.8 0.00017 These calculations were done using a MS Excel spread sheet and shortcut calculations. This data shows that in a larger sample the mass lost per surface area is 0.00045+/- 0.00017 g/mm 2 , which is closer to the industrial standard than my individual data. Discussion/ Conclusion After analyzing the data collected from the five nails I analyzed and comparing it to the data collected by the class (all together 100 nails) it is clear that the more nails included in the average, the more accurate the data is. My average of g/mm 2 was 0.0005 g/mm 2 with a deviation of 0.0001 while the class average was 0.00045 g/mm 2 with a deviation of 0.00017. The national standard for galvanized nails is 0.000305 g/mm 2 . If I were just analyzing my data then I would determine that this batch does not meet the standard, but because I am also comparing the class data, the batch of nails could be considered within the range of the standard. I conclude that the more nails examined, the more accurate the g/mm 2 thus in order to make a completely true analysis I would

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need to test the entire batch. The magnitude of the standard deviations shows that there is a wide range of uncertainty due to error in this lab. I found this lab to have a wide range of error, some that can be removed, others that can only be reduced. The indeterminate error in this experiment is the fact that we cannot fully dissolve the zinc without knowing how much zinc there is on each nail before hand. We can estimate how long it needs to react but without knowing the total mass, and without the zinc being completely uniform we will either not completely dissolve the zinc or some iron could begin to dissolve. This affects the entire lab so that the exact g/mm 2 will not be determined. That is why the more nails
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