MS - PS3.A (A1) - Energy in Chemical Reactions - ASSIGNED (CLF 1/10/14)

Module: Energy in Chemical Reactions

DCI: PS3.A (A1) The term “heat” as used in every day language refers both to thermal energy (the motion of atoms or molecules within a substance) and the transfer of that thermal energy from one object to another.  In science, heat is used only for this second meaning; it refers to the energy transferred due to the temperature differences between two objects.

DCI: PS3.A (B1) The temperature of a system is proportional to the average internal kinetic energy and potential energy per atom or molecule (whichever is the appropriate building block for the system’s material). The details of that relationship depend the type of atom or molecule and the interactions among the atoms in the material.  Temperature is not a direct measure of a system’s total thermal energy.  The total thermal energy (sometimes called the total internal energy) of a system depends jointly on the temperature, the total number of atoms in the system, and the state of the material.

PE: PS1-4 Develop a model that predicts and describes changes in particle motion, temperature, and state of a pure substance when thermal energy is added or removed.

 [Clarification Statement: Emphasis is on qualitative molecular-level models of solids, liquids, and gases to show that adding or removing thermal energy increases or decreases kinetic energy of the particles until a change of state occurs. Examples of models could include drawing and diagrams. Examples of particles could include molecules or inert atoms. Examples of pure substances could include water, carbon dioxide, and helium.]

The ideas we see in this standard are: 

- the term 'heat' refers to both thermal energy and transfer of thermal energy from one object to another

- in science, however, 'heat' is only used for the second meaning, the transfer of energy due to temperature differences between two objects. 

- the temperature of a system is related directly to kinetic and potential energy of the atoms or molecules which the system is made of. 

- the relationship between kinetic and potential energy depends on the type of atoms or molecules and the interactions between them 

- temperature is not a direct measure of the thermal energy of a system 

- thermal energy of a system depends on the temperature, the total number of atoms in the system, and the state of the material.

So - the content in all of this is just the understanding of heat and heat transfer in a system (and how transferring heat changes particle motion).  We can probably ask a question about the use of the term heat and we can ask which factors are related to the temperature of a system.  Other than that, we can stick to the PE. 

Possible Question Starters: 

"Which of the following examples uses the correct scientific definition of the term "heat"?

correct example - a pot of water is heated to boiling on the stove

incorrect example - a student comes inside to escape the afternoon heat

"Kinetic energy of the particles in a solid will increase when which of the following takes place?"

correct answer - thermal energy is added to the solid

incorrect answer - the solid is broken into smaller pieces