The activity introduces the practices from the waste hierarchy (reduce, reuse, and recycle) and reviews the Laws of Thermodynamics. Students deepen their understanding of the laws by deciding which would be the most useful for deciding which practice has the smallest environmental footprint.
Throughout the activity consider how well students:
If two systems are each in thermal equilibrium with a third system, they are in thermal equilibrium with each other. This law helps define the concept of temperature.
Energy can neither be created nor destroyed; it can only be transferred or changed from one form to another. The energy in a system can be converted to heat, or work, or other things, but the total amount of energy always stays the same.
For example, turning on a light does not actually produce energy; it is the conversion of electrical energy to light and heat energy.
This law states that in a closed system, entropy does not decrease.
Entropy is a measure of how ordered or disordered energy is. Ordered energy is useful; an example would be the energy stored in a battery.
Disordered energy is less useful. An example is the energy given off by a fire. During an irreversible process like a fire, the entropy of a system always increases.
Entropy is a thermodynamic property of matter and is related to the amount of energy that can be transferred from one system to another in the form of work. In a system with a fixed amount of energy, the value of the entropy ranges from zero to a maximum. If the entropy is at its maximum, then the amount of work that can be transferred is equal to zero. If the entropy is at zero, then the amount of work that can be transferred is equal to the energy of the system.
The entropy of a system approaches a constant value as the temperature approaches absolute zero. With the exception of non-crystalline solids (glasses), the entropy of a system at absolute zero is typically close to zero.
Matter and energy are conserved in chemical reactions.