As you can see, the Eth stands for thermal energy, and the Eph is phase energy. Ech stands for chemical energy, but we didn't really go over that in class. Let's go over how to do an energy bar chart problem.
The directions were: For each of the situations described below, use an energy bar chart to represent the ways that energy is stored in the system and flows into or out of the system. Below each diagram, describe how the arrangement and motion of the particles change from the initial to the final state.
The situation for problem one was: A cup of hot coffee cools as it sits on the table. As pictured in the photo above, we labeled the first line 0 degrees Celsius (water's freezing point), the second line 25 degrees Celsius (room temperature), the third line 60 degrees Celsius, and the fourth line was 100 degrees Celsius (water's boiling point). We filled in four bars of thermal energy on the initial graph, assuming that the cup of hot coffee was near water's boiling point, and then on the second graph, filled in two bars, because the coffee would probably cool to room temperature. Next, phase energy. As previously stated, liquid is represent with two bars, so we filled in two. We agreed that the phase of the water would not change, so we filled in the same two bars on the final graph. We subtracted the amount of energy bars on the initial graph (six) from the amount on the final graph (four), and we got a difference of negative two energy bars as the event occurred. If the circle between the two graphs is the system of the event, and the event lost two bars of energy, then the arrow with the two bars represents the two bars leaving the system. This is because a large amount of the heat energy of the coffee left as the temperature cooled.
Most of what we did this week was these problems. We whiteboarded them often and had a lot of board meetings. One question I still have from this week is: are the bubbles from boiling water really made up of water vapor? Not air? When we blew bubbles as kids, were the bubbles we blew made of vapor from the bubble solution? Or the air we breathed out? As you can tell I have lots of questions about the bubbles. I participated a lot in learning this week. I really like my table because we're all eager to learn and understand the material we're given, and I think that's really cool. I think I understand the information from this week pretty well.
