Chapter 12 Chapter 1

The objective of Chapter 12: Heating and Cooling was to observe the changes in thermal energy and temperature when substances are heated or cooled. To understand this chapter, students needed to understand the Law of Conservation of Energy, which was taught in 7th grade but has a similar concept to the Law of Conservation of Mass, which students learned about in Chapter 2: Mass Changes in Closed Systems. Both state that the subject matter (energy or mass) cannot be created or destroyed, only transformed. Also, students learned about the characteristic property of specific heat and heat of fusion, and needed the background knowledge gained in Chapter 3: Characteristic Properties in order to fully understand the concept. The purpose of Experiment

Specific heat and heat of fusion are characteristic properties of substances, which allows for even more properties to identify substances with. This is useful when dealing with unknown substances. Students were also able to observe the relationships between thermal energy and temperature. An increase in thermal energy would create an increase in temperature as well, unless the energy is used toward creating a phase change or that there is simply not enough thermal energy to raise the temperature, depending on the specific heat. Thermal energy is the total kinetic energy of all the particles in an object, while temperature is the average kinetic energy of all the particles in the object. If the total amount of energy increases, than the average amount of energy would increase as well. This understanding helps us understand what the energy transfers that are going on that humans cannot physically see, but can see evidence of, like the temperature changing. It was also determined that the temperature ratio of (decrease in temperature of warm substance)/(increase in temperature of cool substance) will be the reciprocal of the mass ratio (mass of warm substance)/(mass of cool substance) when the substances in question are all the same, except for their temperatures and masses. The ratios are inversely proportional to each other and helps explain the reasoning behind temperature changes when 2 samples of the same substance with different temperatures. The evidence collected in this chapter help support the Law of Conservation of Energy, which states that energy cannot be created or destroyed, only transformed. This is supported by idea that the ratio of the increase of thermal energy to the decrease of thermal energy when 2 substances are put in a closed system will always be 1:1. Overall, the information gained in this chapter help