In each pre-class assignment, there is a Podia question that requires numerical, text, and/or image-based response. Each pre-class Podia question is based on the pre-class material and working through the pre-class material will help you formulate your response. Consider the problem and write down/draw out your solution in your class notebook. These questions are designed to hone your skills so that you can analyze and solve mastery problems you will encounter throughout the course.
Two days before the next whole-class session, the pre-class Podia question will become visible in Podia, where you can click on the prompt and submit your solution. [For example, the Podia question for a Wednesday pre-class assignment will be open for submission by Monday evening.] Your submission will only be visible to yourself and your instructor.
You may find Podia sign-in instructions for
- 109-1 (MWF 12:05 PM – 12:55 PM) here
- 109-2 (MWF 2:25 PM – 3:15 PM) here
- 109-3 (MWF 8:50 AM – 9:40 AM) here
Submissions for pre-class Podia activities are due 1 hour before the start of your whole-class. Be sure to submit your response before the due time. If your response shows that you have made full effort to answer the question as well as you could, regardless of whether your answer was correct or not, you will receive full credit for your response.
Day 1 Pre-Class Podia Activity
The halogen elements do not exist typically as atoms, but as diatomic molecules. Molecular bromine, Br2, melts at –7.2 °C and boils at 58.8 °C, while molecular fluorine, F2, melts at –219.7 °C and boils at –188.1 °C. In a table like that pictured below, sketch how you imagine particles of Br2 and F2 to exist in a tiny, closed flask at the indicated temperatures. Where appropriate, your models should include indications of particle kinetic energy and attractive interactions between particles. You may use any notation you wish to depict matter particles, kinetic energy, or attractive interactions between particles.
| T = -190 °C | T = 0 °C | T = 100 °C | |
| Br2 | |||
| F2 |
Select the substance (Br2 or F2) that is more stable as a solid at 0 °C. Support your claim by referring to your models above. Link your claim to this evidence using Coulomb’s law and kinetic energy—why does the relationship of Br2/F2 particle motion and temperature depend on the strength of interactions between particles? (Note: you should not describe the origins of these stronger interactions; we will discuss that topic in time!)
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