CH116lecture22P

CH116lecture22P - UMass Boston Chem 116 CHEM 116...

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UMass Boston, Chem 116 ©H.±Sev ian CHEM 116 Electrochemical Cells Lecture 22 Prof. Sevian Today’s agenda z Big picture of electrochemistry z Redox reactions and oxidation numbers (last lecture) z Charge flow in electrochemical cells and diagramming a cell z Using the mathematical model to predict current and voltage under standard and non-standard conditions Announcements z Exam 3 is this Thursday, Dec 4 z Final exam has been scheduled for Tuesday, Dec 16, 3:00pm in
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UMass Boston, Chem 116 ©H.±Sev ian SOH e ¯ method of balancing redox equations Separate the redox reaction into reduction and oxidation halves, and then for each half: z S pecies – in the species that contains the element whose oxidation number is changing, balance that element z O xygen – balance the oxygens by adding H 2 O on whichever side of the equation is missing oxygen z H ydrogen – balance the hydrogens by: z If acid solution, add H+ to one side z If basic solution, add OH ¯ to one side and H 2 O to the other side, so H 2 O is added to side needing more H atoms z E lectrons – balance the charge on both sides by adding electrons ( e ¯ ) to whichever side requires negative charge Now add the two half reactions together in such a way that the electrons cancel (least common multiple) Practice using SOH e method 1. Cu ( s ) + NO 3 ¯( aq ) Cu 2+ ( aq ) + NO 2 ( g )
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UMass Boston, Chem 116 ©H.±Sev ian Practice using SOH e method 2. Cd ( s ) + NiO 2 ( s ) + H 2 O ( l ) Cd(OH) 2 ( s ) + Ni(OH) 2 ( s ) in acid
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This note was uploaded on 12/02/2011 for the course PHYSICS 235 taught by Professor Staff during the Fall '08 term at Rutgers.

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CH116lecture22P - UMass Boston Chem 116 CHEM 116...

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