E115_Problem_Set_28

# E115_Problem_Set_28 - the oxidant Lead oxide(which does not...

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e 115 Engineering Thermodynamics Fall 2009 University of California Problem set 28 Due: Friday, December 4 th , in lecture 1) (15 points) The following plot shows the free energy of an A-B solution at 1000 K. -8000 -6000 -4000 -2000 0 0 0.2 0.4 0.6 0.8 1 G (J/mole) X B

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E115 Problem Set 28 A. M. Glaeser 1 2 1 a) What are the chemical potentials of A and B in a solution where X B = 0.4 ? X B = 0.45 ? (4 points) b) What are the activities of A and B in solution when X B = 0.4 ? X B = 0.45 ? (4 points) c) What type of solution is this? (2 points) d) At what composition does a A = a B ? (2 points) e) What are μ A and B when a A = a B ? (3 points) 2) (15 points) In lead refining, the antimony impurity is removed from liquid lead by selective oxidation using air as
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Unformatted text preview: the oxidant. Lead oxide (which does not dissolve in metals) is added to the alloy; antimony takes oxygen from this oxide by the reaction below. The resulting antimony oxide precipitates out of the solution. Meanwhile, the lead oxide, reduced to lead, dissolves in the alloy. At a temperature of 887°C, assuming the thermodynamics of liquid Pb-Sb alloys is adequately described by an ideal solution, estimate the lowest possible antimony concentration that can be attained. 2 Sb ( l ) + 3PbO ( l ) = 3Pb ( l ) + Sb 2 O 3 ( l ) Δ G °= − 105, 414 − 17.972 T J ⋅ mole-1 of Sb 2 O 3 formed...
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E115_Problem_Set_28 - the oxidant Lead oxide(which does not...

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