PHYS 1090: Fundamentals of the Physical Universe

Unit 15: Oxidation and Reduction
Due Friday December 2, 2011
15 points

Answer one of the following questions.

These questions are for you to combine different ideas from the unit and apply them to situations not directly addressed in class or in the textbook.  Think about the situation, and about the physics that applies to it.  See me for help if you are stuck.

1. Chemistry’s irreducible minimum.

Noted chemist and author Peter W. Atkins has stated that the heart of chemistry comprises just a few concepts.  We have not covered all of the concepts on his list, but we have explored quite a few of them.  Eight of his concepts are listed below.

1. All matter consists of atoms.
2. Atomic structure accounts for the periodic behavior of elements, as manifest in the columns and rows of the periodic table.
3. Bonds between atoms form by electron pair-sharing.
4. Molecular shape is of paramount importance to the behavior of the compound.
5. There are residual forces between molecules beyond covalent bonding.
6. Energy is conserved.
7. Energy and matter tend to disperse.
8. There are barriers to chemical reactions.

Pick four of these concepts. For each of your four, describe one activity or lesson we did in this class to address that concept.

2. Decomposition of H₂O₂.

Hydrogen peroxide (H₂O₂, connected as H–O–O–H) can decompose to form oxygen gas (O₂) and water (H₂O) by the reaction

2 H₂O₂ → O₂ + 2 H₂O.

Write dot structures for every molecule in this reaction and track each atom from the starting materials to the products.  For each atom, indicate if it is oxidized, reduced, or neither in the reaction.

3. Pure oxygen.

Explain, using chemical principles we have learned in this class, why the wood and the steel wool burned so much more vigorously in pure oxygen than in air.

4. Additional examples.

In lab, we carried out a few examples of redox reactions.  Identify two redox reactions in addition to the ones done in lab.  Provide balanced equations for the reactions if you can, identify the materials that are oxidized and reduced, and give some background, in a paragraph or so, about each reaction.

If you submit any part of this assignment as an electronic document, upload it (or them) to Sakai using the “Assignments” tool.  That way I will be able to find them easily and I will not tend to lose them.  Or, you may enter your text directly into Sakai’s “Assignments” tool.  Hard copy submissions are also allowed.

In the holiday spirit: Do not turn in paper that has ragged edges!  If you write your work in a spiral-bound notebook, trim the edge before submitting it.  Papers with ragged edges will be returned unmarked.