Chapter09 - Applied Science Department (ASD) Centre for...

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PCE 0015 Chemistry for Engineers Foundation in Engineering ONLINE NOTES Chapter 9 ELECTROCHEMISTRY FOSEE , MULTIMEDIA UNIVERSITY (436821-T) MELAKA CAMPUS, JALAN AYER KEROH LAMA, 75450 MELAKA, MALAYSIA. Tel 606 252 3594 Fax 606 231 8799 URL: http://fosee.mmu.edu.my/~asd/ Applied Science Department (ASD) Centre for Foundation Studies and Extension Education (FOSEE)
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PCE0015 Chemistry For Engineers Chapter 9 9.1 Redox Reactions 9.2 Types of Redox Reactions 9.3 Galvanic Cells 9.4 Electrolytes and Nonelectrolytes 9.5 Electrolysis 9.6 Quantitative Aspects of Electrolysis (Faraday’s Law) 9.7 Applications of Electrolysis Upon completion of this chapter, you should be able to : 1. Understand the redox reaction and write the redox equation. Redox reactions involve the transfer of electrons. Equations representing redox processes can be balanced using the ion-electron method. 2. Define types of redox reactions, especially metal displacement and a way to predict the reactions by referring to electrochemical series. 3. Explain the basic concept of galvanic cells and cells diagram. In a galvanic cell, electricity is produced by a spontaneous chemical reaction. Oxidation and reduction take place separately at the anode and cathode, respectively, and the electron flow through an external circuit. 4. Distinguish between electrolytes and nonelectrolytes. 5. Understand the concept of electrolysis by the examples given. 6. Determine the quantitative aspects of electrolysis by applying Faraday’s Law 7. Understand the application of electrolysis in electroplating __________________________________________________________________________________ HST/MAM 2/ 11
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PCE0015 Chemistry For Engineers Chapter 9 9.1 REDOX REACTIONS Electrochemistr y is the area of chemistry concerned with the interconvertion of chemical and electrical . For example, a battery is an electrochemical cell, a device for interconverting chemical and electrical energy. A battery takes the energy released by a spontaneous chemical reaction and uses it to produce electricity. In redox reactions electrons are transferred from one substance to another. The reaction between magnesium metal and hydrochloric acid is an example of a redox reaction : 0 +1 +2 0 Mg( s ) + 2HCl( aq ) MgCl 2 ( aq ) + H 2 ( g ) The numbers above the elements are the oxidation numbers of the elements. The loss of electrons by an element during oxidation is marked by an increase in the element’s oxidation number. In reduction, there is a decrease in oxidation number resulting from a gain of electrons by an element. In this reaction, Mg metal is oxidized and H + ions are reduced. Balancing Redox Equation. The equations for the two half reactions are balanced separately and then added together to give the overall balanced equation. For example, the reaction between zinc powder and argentums nitrate solution. The following steps are needed: 1) Separate the equation into two half-reaction Zn( s ) Zn 2+ ( aq ) + 2e - Ag + ( aq ) + e - Ag( s
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This note was uploaded on 04/10/2010 for the course CHM CHM101 taught by Professor Woljaong during the Fall '07 term at Multimedia University, Cyberjaya.

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Chapter09 - Applied Science Department (ASD) Centre for...

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