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.

chem blog - mass and change

      Over the past week, we learned about changes in mass and the exploding paint can. These main ideas connect with each other because the exploding paint can was a change of mass. Most of the changes of mass were caused by chemical reactions but some of the changes of mass stayed the same. We performed six experiments to see the change in mass and one experiment as a class for the exploding paint can.

Exploding Paint Can We filled a small and a big paint can with methane, which is a gas lighter than air itself, and lit it on fire. In the beginning, the flame was blue at the bottom and fading to red and yellow near the top. As the fire started to die, the flame became more of a blue little bulb. When the fire finally died, the paint cans both made a loud bang that startled most of us. For the small paint can, it jumped off the table and fell onto the floor. However, for the big paint can, it only tilted, the reason might be that the can wasn't sealed tightly enough.

Station 1 We first massed a pie tin and used it to mass a piece of steel wool. Then we pulled apart the steel wool and massed it again. We thought that the mass would stay the same, mainly because no particles were lost or gained. As it turned out, the pulled apart steel wool was lighter than the original by 0.2 grams, most likely because when we were pulling it apart, bits of the steel wool didn't land in the pie tin, therefore attributing to the lighter mass.

whiteboard of the particles of the steel wool and pulled apart steel wool

Station 2 We first massed the pulled apart steel wool in a pie tin. We then picked up the pulled apart steel wool with a pair of tongs and placed the burner in the pie tin. Then we lit the burner and passed the steel wool in and out of the flame. As the steel wool was burning, flakes of it fell off and it turned a dark blue color. Before we burned steel wool, it had a mass of 5.612 grams. After we had burned the steel wool, it had a mass of 6.1 grams. I thought that the steel wool would get lighter, but in contrast, it grew heavier by 0.488 grams, due to the chemical reaction that happened.

steel wool before being burned

steel wool after being burned

steel wool being burned

Station 3 We first found the mass of the vial and ice. We then warmed the vial in our hands to speed up the melting. After the ice was melted, we massed the water and vial. The mass of the vial and ice was 10.6 grams. The mass of the water and vial was 10.5 grams. The ice and the water should've been the same mass because no chemical changes were made. The human error that may have occurred is that we forgot to zero our scales.

Station 4 There was vials of blue-colored CaCl2 and clear Na2CO3. We first massed CaCl2 and Na2CO3 together. We then combined the two solutions together and massed the mixture. The mixture turned out a cloudy blue. The mass of the two solutions was 53 grams. The mass of the mixture was 41.3 grams. The result was the mixture being heavier than the separate vials by 11.7 grams, which was caused by a chemical reaction from the two solutions. 

blue-colored CaCl2 and clear Na2CO3

The cloudy blue mixture

Station 5 We first filled a vial with water and put a sugar cube in the cap. We then massed the vial with the water and cap with sugar. Then we gently shook the vial and watched the sugar dissolve. Finally, we massed the dissolved sugar solution. The mass of the sugar vial before it was dissolved was 45.23 grams. The mass of the dissolved sugar vial was 45.23 grams. The sugar vial before it was dissolved turned out to be the same mass as the dissolved sugar vial because no chemical change was added.

Station 6 We first filled a vial halfway with water and a fourth tablet of alka-seltzer in the cap of the vial. We then put the cap and vial on the balance to mass it out. Then we put the alka-seltzer in the water, watched it dissolve, and then massed it. The mass of the vial and cap before the alka-selzter 34.96 grams. The mass of the dissolved alka-seltzer in the vial and cap was 33.88.  The change in mass was -1.08 grams. I was taken aback by this result because I thought it would increase in mass because two separate materials were combined. It may have decreased because of the bubbles making it lighter. 

dissolved alka-selzter in vial

      We came to know and understand the ideas we learned this week by performing experiments and making charts and histograms based off out data. Another thing we did was share our ideas on whit boards and had discussions about that topic.

our data for station 1 (left)
our histograms for station 1 (right)

      Questions I still have is why the burned steel wool had more mass than the original. I participated okay this week because there were some moments where I got distracted. If I had to rate my understanding of all the ideas from this class, I would rate myself an 8.5 because I understand most of the concepts, I just have a few questions. I need to work on staying more focused and organised.