Homework 10

Homework 10 - (a Aluminum and cast iron(b Cadmium and...

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ENMA 300/ENME 382 HW 10 Due. Nov. 28, 2011 1. Callister 16.2 (modified) (a) Compute the voltage at 25°C of an electrochemical cell consisting of pure lead immersed in a 5 × 10 –2 M solution of Pb 2+ ions, and pure tin in a 0.25 M solution of Sn 2+ ions. (b) Write the spontaneous electrochemical reaction. (c) What is one common application for Pb-Sn materials? If the Pb-Sn were used near the ocean (on a ship or near the shore), could the reaction above occur? 2. Callister 16.4 An electrochemical cell is constructed such that on one side a pure Zn electrode is in contact with a solution containing Zn 2+ ions at a concentration of 10 –2 M. The other cell half consists of a pure Pb electrode immersed in a solution of Pb 2+ ions that has a concentration of 10 –4 M. At what temperature will the potential between the two electrodes be +0.568 V? 3. Callister 16.5: For the following pairs of alloys that are coupled in seawater, predict the possibility of corrosion; if corrosion is probable, note which metal/alloy will corrode.
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Unformatted text preview: (a) Aluminum and cast iron (b) Cadmium and zinc (c) Low-carbon steel and copper 4a. What is CPR? Why is it important? b. A thick steel sheet of area 100 in. 2 is exposed to air near the ocean. After a one-year period it was found to experience a weight loss of 485 g due to corrosion. To what rate of corrosion, in both mpy and mm/yr, does this correspond? 5. This is a study problem. You do not have to submit the answers. The solutions will be posted. Nickel experiences corrosion in an acid solution according to the reaction Ni + 2H + → Ni 2+ + H 2 The rates of both oxidation and reduction half-reactions are controlled by activation polarization. (a) Compute the rate of oxidation of Ni (in mol/cm 2-s) given the following activation polarization data: For Nickel For Hydrogen i = 10 –8 A/cm 2 i = 6 × 10 –7 A/cm 2 β = +0.12 β = –0.10 (b) Compute the value of the corrosion potential....
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This note was uploaded on 04/03/2012 for the course ENME 382 taught by Professor Christou during the Spring '12 term at Maryland.

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