chem blog - white boards and zeros

      During this past week, we compared our data for our experiments from the previous week, made histograms based off the data, and created particle white boards of what happened. These main ideas connect because the data allowed us to make a histogram and both the histogram and white boards allowed us to understand what we were learning. Since we made a histogram and white board for station #1 last week, this week we made the histograms and white boards for stations #2-6. We also looked into significant and placement zeros. 

Station #2 data, histogram, white board (dhw) For this station, we massed a pulled apart steel wool and a burned steel wool. The overall class data was varied. It ranged from 0.48 grams to 0.9 grams. My group had a 0.488 grams change in mass. The reason why these results are so varied is because everyone had different amounts of steel wool when they were massed. For the white board, my group drew the pulled apart steel wool particles, before and after it was burned. The before particles were black dots, evenly spaced. In the after picture, the particles of the steel wool was black and blue, due to a chemical reaction that happened. We also showed how bits of the blue particle fell off the steel wool.

white board of the steel wool burning

class data (left)
histogram (right)

Station #3 dhw At this station, we massed an ice cube before and after it melted. The class data was similar to each other, except for two outliers. It ranged from -0.1 grams to 0.9 grams. The outliers were 0.9 grams and 0.68 grams, My group had a -0.1 gram change in mass. The reason for the outliers might be that they forgot to add the cap onto the scale after the ice had melted. For the whiteboard, my group drew the ice particles, before and after it was melted. For the ice particles, we drew blue dots representing water and red dots representing air particles all mixed together. For the melted ice particles, we drew the blue dots on the inside and red dots on the outside. 

whiteboard of ice melting

class data (left)
histogram (right)

Station #4 dhw At this station, we massed CaCl2 and Na2CO3 before and after they were mixed together. The class data was almost the same, except for one outlier. My group had a -11 change in mass, which was also the outlier.  The reason for this outlier is that when we were massing the mixture, we forgot to add the empty vial onto the scale. On the whiteboard, we drew particle pictures of CaCl2 and Na2CO3 before and after they were combined. On the before section, in the first vial, we drew green circles representing calcium chloride and blue circles representing water, all mixed together. In the second vial, we drew purple circles representing sodium carbonate and blue circles, all mixed together. On the after section, the first vial had purple, green, and blue dots all mixed together. The purple and green dots had triple lines connecting them, showing that those particles might have bonded. 

whiteboard of the mixture

class data (left)
histogram (right)

Station #5 dhw  For this station, we massed a sugar cube and a vial of water, before and after the sugar cube dissolved. The class data ranged from -0.4 grams to 0.9 grams. The outlier was 0.9 grams. My group had no change in mass. The reason for the outlier may be that they didn't mass the cap of vial before the sugar had dissolved. For the whiteboard, my group drew the sugar cube and water particles, before and after the sugar had dissolved. In the before picture, the purple dots represent the sugar particles and the blue particles represent the water particles. In the after picture, the vial contains blue and purple dots.

whiteboard of the dissolving sugar

class data (left)
histogram (right)

Station #6 dhw For this station, we massed the Alka-Seltzer and vial of water before and after the Alka-Seltzer dissolved. The overall class data was very close to each other. The data ranged from -0.103 grams to -0.05 grams. My group had a -0.05 grams change in mass. I think that the reason for the dissolved Alka-Seltzer to lose mass is because gas bubbles escaped the vial. On the whiteboard, we drew Alka-Seltzer particles represented by black circles and water particles represented by blue circles. After the Alka-Seltzer had dissolved, we drew blue and black circles mixed together and black dots floating upward to represent the gas bubbles. 

whiteboard of the dissolving Alka-Seltzer

class data (left)
histogram (right)

Zeroes We received a packet that had problems about significant and placeholder zeros. Significant zeros are zeros that are between significant digits (non zero). Placeholder zeros are zeros that tell you what place the number should be at. In the packet, there was a page that told us specific rules for significant and placeholder zeros. As my group was working on this, we found that some numbers could be true for more than one rule, which greatly confused us.
      We came to know and understand the ideas this week by working and talking together as a class to break down the material and data that was given. Questions I still have is about significant and placeholder zeros. I often can't tell which is which. I think my participation this week was very good because I discussed all the topics our class landed on with my group. If I had to rate my understanding of all the ideas from class, I would rate myself a 9 because I understand most but not all of the concepts that we learned. I feel like I don't need to work at anything specific at this moment.