Chemistry
Chapter 3: 8-9
Homework
Oxidation-Reduction Reactions
Chapter 3:8-9 Homework
- Reading Preparation
- WebLecture
- Study Activity
- Preparation work for chat
- Online Quiz
- Lab Instructions
Reading Preparation
Textbook assignment: Read Kotz and Triechel, Chemistry and Chemical Reactivity Chapter 3: Sections 8 to 9.
Study Notes
3.8 Oxidation-Reduction Reactionsl. All oxidation-reduction reactions (redox reactions) involve electron transfers between the reactants to form the new components. While it may seem like the rules for redox reactions and assignment of oxidation numbers are somewhat arbitrary, they are based on the electron configuration and affinity characteristics of the atoms involved in the exchange.
3.9 Classifying Reactions. A reaction occurring in water-based solution is often classified as one (or more!) of four types: precipitation, salt-forming acid/base, gas-forming, or oxidation-reduction (electron transfer). Note the characteristics of each, and that a given reaction may fall into more than one classification category.
Oxidation-Reduction Reactions
| Half-reaction | Electron Transfer | Result |
|---|---|---|
| X → Xn+ + n e- | X tranfers electrons to Y | X is oxidized and is the reducing agent |
| Y + ne- → Yn- | Y accepts electrons from X | Y is reduced and is the oxidizing agent |
| Atom or Molecule Type | Oxidation Number | Example |
|---|---|---|
| Atom in Pure Element | Zero | I2: each I = 0 |
| Monatomic ion | Charge on ion | Mg2+: +2 |
| Fluorine in compound | -1 | FI: F is -1, I is therefore +1 |
| Oxygen in compound | -2 | H2O: O is -2, each H is +1 EXCEPTIONS: in FO, O is +1 in peroxides, O is -1 in superoxides, O is -1/2 |
| Halogens Cl, Br, and I in compounds | -1 | NaCl: Cl is -1; Na is therefore +1 Exceptions: with O or F ClO-: Cl is +1 |
| Hydrogen | +1 | H2O: O is -2, each H is +1 EXCEPTIONS: in metal hydrides, H is -1 CaH2: Ca is +2, each H is -1 |
| Neutrally charged compound | Sum of oxidation values is zero | H2O: 2 * -+1 + -2 = 0 |
| Charged polyatomic ion | Sume of oxidation values equals charge | PO4-3- Each O: -2 total -8 P: +5 Net: -8 + 5 = -3 |
Web Lecture
Read the following weblecture before chat: Reduction-Oxidation (REDOX) Reactions
Study Activity
Videos for Chapter 3: Chemical Equations
Review the Videos at Thinkwell Video Lessons under REACTIONS IN AQUEOUS SOLUTIONS.
- Oxidation-Reduction Reactions
Chat Preparation Activities
- Essay question: The Moodle forum for the session will assign a specific study question for you to prepare for chat. You need to read this question and post your answer before chat starts for this session.
- Mastery Exercise: The Moodle Mastery exercise for the chapter will contain sections related to our chat topic. Try to complete these before the chat starts, so that you can ask questions.
Chapter Quiz
- Required: Complete the Mastery exercise with a passing score of 85% or better.
- Go to the Moodle and take the quiz for this chapter.
Lab Work
LAB #1 GUIDED INQUIRY -- Phase III (Experiment #2)
Determination of water in copper sulfate pentahydrate and sodium hydrogen carbonate
What is the Amount of Water in Common Hydrates?
For this week: Decompose sodium hydrogen carbonate in a modified Solway process, calculating percent yield and percent atom economy.
References:
- IGHCE Lab 9.1 and HSCKM III-1 Observe a Composition Reaction
- IGHCE Lab 9.2 and HSCKM III-2 Observe a Decomposition Reaction
- (Alternative lab) Water in Hydrates
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