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Chapter 3: 8-9

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Oxidation-Reduction Reactions

Chapter 3:8-9 Homework

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-reactionElectron TransferResult
X → Xn+ + n e-X tranfers electrons to YX is oxidized and is the reducing agent
Y + ne- → Yn-Y accepts electrons from XY is reduced and is the oxidizing agent
Atom or Molecule TypeOxidation NumberExample
Atom in Pure ElementZeroI2: each I = 0
Monatomic ionCharge on ionMg2+: +2
Fluorine in compound-1FI: F is -1, I is therefore +1
Oxygen in compound-2H2O: 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-1NaCl: Cl is -1; Na is therefore +1
Exceptions: with O or F
ClO-: Cl is +1
Hydrogen+1H2O: O is -2, each H is +1
EXCEPTIONS: in metal hydrides, H is -1
CaH2: Ca is +2, each H is -1
Neutrally charged compoundSum of oxidation values is zeroH2O: 2 * -+1 + -2 = 0
Charged polyatomic ionSume of oxidation values equals chargePO4-3-
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

Optional Websites:

If you are still having problems, yo may find the oxidation-reduction reactions from Lumen Learning useful, as well as this oxidation numbers calculator.

Chat Preparation Activities

Chapter Quiz

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.