Handouts_C11 - Electrochemistry Redox Reaction Review...

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1 Chapter 11 Electrochemistry Big Idea: Electron transfer in a chemical reaction is both material 1 Redox Reaction Review Galvanic Cells Thermo of Electrochemistry and concentration specific. If the process is spontaneous the transfer of electrons can be used to produce a current and drive electrical devices. Nernst Equation Batteries / Fuel Cells Electrolytic Cells Electrochemistry Redox Reaction Review 1. The oxidation number (ON) of an element uncombined with another element is zero: Na(s) ON = 0, and H 2 (g) ON = 0. 2. For monatomic ions, the charge is the ON: Na + ON = +1. 3. The ONs of elements in group 1 equal 1 (ex. Lithium ON = +1) ONs of elements in group 2 equal 2 (ex. Magnesium ON = +2), when the atoms are Assigning Oxidation Numbers 2 in a compound. 4. The ON of fluorine is always -1 in compounds. 5. The ON of the other elements in group 7 usually equal -1 when the atoms are in a compound. 6. The ON of oxygen is usually -2 in compounds. Exceptions are fluorine compounds and peroxide (a compound that contains an O-O single bond). 7. Hydrogen's ON is +1 when combine with non metals and -1 when combined with metals. 8. The sum of the ONs of all the atoms in a species is equal to its total charge. Determining Which Element is Oxidized/Reduced Step 1: Assign oxidation numbers. Redox Reaction Review Electrochemistry 3 Step 2: Use oxidation numbers and OIL RIG to identify which element is oxidized and which is reduced. Note: If the question asks which substance is oxidized, instead of giving the element that is oxidized give the compound containing the element. Oxidizing Agent: A species that removes electrons from a species being oxidized in a redox reaction. Note: Oxidizing agent is the species being reduced Redox Reaction Review Electrochemistry 4 Reducing Agent: The species that supplies electrons to a substance being reduced in a redox reaction. Note: Reducing agent is the species being oxidized. Balancing Redox Reactions in Basic Conditions Step 1: Write unbalanced half reactions. Step 2: Balance half reactions except for O and H. Step 3 : Redox Reaction Review Electrochemistry 5 : Balance O by using H 2 O. Step 4: Balance H by using H 2 O and OH - (H 2 O OH - ). Step 5: Balance electrons in each half reaction. Step 6: Multiply half reactions by an integer so that number of electron match then add reactions together.
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This note was uploaded on 04/27/2010 for the course CHEM 05785 taught by Professor Feldwin during the Spring '10 term at UCSB.

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Handouts_C11 - Electrochemistry Redox Reaction Review...

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