Enthalpy Evaluation Information Page

Short discussion of the energy differences between endo and exothermic reactions. Very clearly focused on the energy being tied to the bonds that are being broken and formed and how the balance between the two determines end vs. exo.

Drew reaction coordinate diagrams to explain.

Enthalpy of reaction - amount of energy being emitted or taken in during a chemical reaction as a result of bonds being broken and formed.

Gives example of nitroglycerin as an exothermic reaction (shows molecule), then talks about dynamite - stabilizes nitroglycerine by wrapping it.

Flow chart looks at amount of energy required to break bonds in reactants and the amount released when new bonds form in products and connects that to endo and exothermic reactions.

Talks about thermite reaction and shows energy diagram for the reaction (exothermic reaction). Shows enthalpy diagram.

If you turn the reaction around, enthalpy is the same amount but opposite sign.

Gives example of dissolution of ammonium nitrate. Moves to Born-Haber cycle and how it is a bunch of small reactions - example if making LiF out of Li and F2 gas - does not talk about what makes different parts endo or exothermic.

4:36-7:20 is Hess' law problem. Did you learn is the end part.

Explains enthalpy and that we measure change in enthalpy, not enthalpy.

Shows a neutralization reaction on a reaction coordinate diagram and an endo reaction.

This lesser viewed video pulls together a strong conceptual description of endothermic and exothermic reactions.

The video clearly articulates the energy changes associated with both bond making and breaking. In doing so, it makes strong connections between the symbolic and particulate representations.

Throughout the video, the narrator uses the core idea of energy with enough depth that met the Causal Mechanistic Reasoning expectations when answering the question “What results in an exo or endothermic reaction?”

The video itself was strong in all aspects of Mayer’s multimedia principles that were assessed.

This video provides a very good summary of how the balance of energy required to break and form bonds results in the net change in energy.

The video provides macroscopic examples and links those to the symbolic graphical representations of an energy diagram.

In providing the description, the video employs the Energy core idea and does so in enough depth to achieve a Causal Mechanistic Reasoning answer.

The video also provides a reminder of the key expected learning outcomes at the end.

This video begins with very clearly articulated learning objectives.

The video addresses the concept of enthalpy by defining it and provides a representation of the macroscopic impacts that enthalpy can have (changing temperature as a result of a chemical reaction).

Lastly, the video takes an in-depth look at the reaction energy diagram and shows the difference in representation between an exothermic and endothermic reaction, including activation energy.

The video effectively addresses the idea of Energy as a core idea as well as using the Science Practice of constructing explanations to explain why neutralization reactions are exothermic.

Because the video did not bring in a real world phenomena, it did not meet the criteria for Science Practices.

Right at the beginning of the video, there was one potentially misleading part where it was stated that molecules could not react if we did not add heat.

Although activation energy is indeed required for reactions, it is often the case where ambient temperature provides enough energy for the reaction to proceed without additional heat.

Throughout the video, the narrator can be seen on screen which can be distracting for some viewers.

The video also contains a significant section on Hess’s Law.

This is used through the process of rearranging and adding equations to determine the change in enthalpy for a reaction.

Although nothing is incorrect, this aspect was outside of the broader conceptual focus defined for this topic.

The video itself has the speaker shown constantly and has captions directly on the video (cannot be turned off).

Each of these can be distracting for some students.

The video also lacks the level of depth to achieve causal mechanistic reasoning.

In many ways, the video seems to focus more on being able to draw out the reaction coordinate diagram rather than fully understanding the concepts behind it.