Quantities associated with temperature and phase changes

In C.1 Thermodynamics in Earth’s Systems, students identify specific heat capacity graphically through interactions with a simulation, but it is not distinguished from heat capacity. Students also develop latent heat of fusion–this can be named as such but does not have to be. Other similar quantities could be introduced here if needed, but this should be done in the context of related phenomena through a question like, How much energy is transferred in other phase changes?

Enthalpy and Hess’s Law 

C.5 Energy from Chemical & Nuclear Processes supports students in developing nuanced models of energy transfer in and out of fields to explain endothermic and exothermic reactions. Students quantify these energy transfers as bond energies. Enthalpy is a particular measure of energy that is not necessary to initially explain the energy transfers in combustion and other chemical systems. Although Hess’s law is often useful at the system level, it is not introduced in this unit so that students can focus on particle-level field thinking to tie math to the mechanism. This field thinking is necessary in order to help students shift from common understandings of breaking bonds “releasing energy,” as if the bonds are containers that energy can leak out of.

Laws of Thermodynamics

Students develop the ideas behind all three laws of thermodynamics in the OpenSciEd course. In C.1 Thermodynamics in Earth’s Systems, students consider model Earth systems to develop initial ideas of energy conservation (first law), which they quantify and confirm through simulations of melting in Lesson 10. The concepts of the third law are introduced in C.5 as students realize that a different temperature system–the Kelvin scale–is needed to use the combined gas law. The ideas behind the second law are developed in the physics course, in P.1 Energy Flow from Earth’s Systems, as students recognize that electricity-generating systems are inherently inefficient. These laws (and related concepts, like entropy) are not named by default because such an emphasis could push students toward using vocabulary terms as shorthand without fully developing the ideas behind them. However, if required, students could be introduced to the names of these ideas as they build them.

References

American Chemical Society. (2018). ACS Guidelines and recommendations for teaching middle and high school chemistry. www.acs.org /mshsguidelines

National Governors Association Center for Best Practices and Council of Chief State School Officers. (2010). Common core state standards. https://www.thecorestandards.org/

National Research Council. (2012).  A Framework for K-12 Science Education: Practices, Crosscutting Concepts, and Core Ideas. The National Academies Press. https://doi.org/10.17226/13165

NGSS Lead States. (2013). Next generation science standards: For states, by states. The National Academies Press.