SG/Chem Blog 2

Over the last week in Sustainable Green Chemistry, we did lots of stuff. For most of the week we did lots of particle diagramming of experiments we did last week. We also learned about the problems that using different kinds of measuring tools can pose and significant figures.

Part 1: Particle Diagramming

Last week we did quite a few experiments with mass and change. To list a few, we took the mass of ice before and after it melted , and the mass of a sugar cube before it dissolved. If you want to read more about these experiments, check out last weeks blog post. This week we diagrammed what we think happened. We did this using particle diagrams.

*Unrelated particle diagram example*

While diagramming, we shared our data, we found that in most cases the mass changed very little or not at all. This is because of the Property of Conservation of Mass, this property causes the mass of an object to stay the same through any chemical reaction. The only experiment we did where this did not apply was when we burned steel wool. For some reason it gained mass, I think that it gained mass because of some reaction of the methane we were burning with the steel wool, or a reaction from the iron in the steel and the air, maybe forming iron oxide. I hope that Dr. Finnan will shed some light on this conundrum.

While doing particle diagramming, I found it interesting that sometimes everyone had very similar models but, other times the models were all very different. I think we had some very well educated discussions about our models in class.

Part 2: Significant figures and measurements

Significant figures are the digits that are important in a number, to find the significant figures, you follow a few simple rules, I will list them below:

1) ALL non-zero numbers (1,2,3,4,5,6,7,8,9) are ALWAYS significant.

2) ALL zeroes between non-zero numbers are ALWAYS significant.

3) ALL zeroes which are SIMULTANEOUSLY to the right of the decimal point AND at the end of the number are ALWAYS significant.

4) ALL zeroes which are to the left of a written decimal point are ALWAYS significant.

                              5)ALL exact counts (20 students) have INFINITE significant figures

Significant figures are important because they tell us how to round our numbers, they also help make our numbers more precise. Both of these reasons are very important for science because having accurate data is important. Another step towards having accurate data is having accurate measurements. For example, different scales will measure to a different level of accuracy (1g,1.0g,1.00g etc...). Also when taking measurements you only estimate 1/10 of the smallest marking on the tool.

Conclusion:

In conclusion, the last week has been very eventful in Sustainable Green Chemistry. We did lots of particle diagramming, and measuring. This week has made me really look forward to the next few weeks. 

See you next week! :)