Design a spherical tank, with a wall thickness of 2 cm that will ensure that no more than 50 kg of hydrogen will be lost per year. The tank, which will operate at 500°C, can be made of nickel, aluminum, copper, or iron. The diffusion coefficient of hydrogen and the cost per pound for each available material is listed below.
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Diffusion Data
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Material
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D0 (cm2/s)
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Q (cal/mol)
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Cost ($ lb)
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Nickel
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0.0055
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8,900
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4.10
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Aluminum
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0.16
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10,340
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0.60
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Copper
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0.011
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9,380
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1.10
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Iron (BCC)
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0.0012
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3,600
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0.15
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