What’s in a BB?

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In this exploration we were trying to find out, “what metals are in a BB”. In order to distinguish between all the different metals, I had to find out the density of the BBs, because each metal has a unique density. To find out the density of the BBs I filled a graduated cylinder with 20ml of water. The mass of this was 60.41g. I then filled the grad cylinder with BB’s until the water was up to 25ml. I did this two more times and weighed the grad cylinder when the water was at 25, 30, and 35ml. So, all of these measurements are:

1. Grad cylinder with water- 60.41g

2. Grad cylinder with 20ml water and 5 ml BBs-100.36g

3. Grad cylinder with 20ml water and 10g BBs-156.59g

4. Grad cylinder with 20ml water and 15g BBs-175.51g

To find the mass of just the BBs I subtracted the mass of the grad cylinders by the mass of the water. I got the following data:

1.  100.36-60.41=39.95g

2.  136.59-60.41=76.18g

3.  175.51-60.41=115.1g

Now, I can FINALLY find the density. Density is mass/volume.

1.  39.95/5=7.99g/cm^3 or 8

2.  76.18/10=7.618g/cm^3 or 8

3.  115.1/15=7.673g/c^3 or 7.7

These densities match closest with Steel, Zinc, and Iron. So, according to this lab, BBs are made up of Steel, Zinc and Iron. The data in my experiment could have been made more reliable by using Significant Numbers. What are significant numbers you ask? They are the number of reliable digits in a measurement or calculation. The last number is also always an estimate. So, in this experiment the scale I used only went to the 1/100th place. That means I could guess the 1/1000th place, but If the scale had gone to the 1/1000th place, then I would know what is was for sure, and it would be reliable. Since the scale cannot get any more precise, their was some problems with precision. Many metals have very similar densities, so the smallest change in decimal can result in a density for a totally different metal. If I could have measured a more accurate number, then the experiment may have resulted in Copper also being in the BBs.  IMG_1668[1]

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