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Unformatted text preview: Chemistry 3250 Ethics case study 2: Statistics vs point measurements Adapted from “Nearing the Limit” case study, J. Kovac, The Ethical Chemist , Pearson: Upper Saddle River, NJ, 2004 Due: Tuesday, March 6, 12:15 p.m. Cyanide and gold mining • Cyanide is used in gold mining to extract gold from low-grade ores. The reaction is 4 Au ( s ) + 8 CN- ( aq ) + O 2 ( g ) + 2 H 2 O ( l ) → 4[ Au ( CN ) 2 ]- ( aq ) + 4 OH- ( aq ) . The gold is then recovered by electrodeposition. • This process is typically carried out right at the mine site. • Cyanide is extremely toxic, so cyanide contamination of water is always a concern. • Cyanide monitoring is routinely performed near mines. • In Canada, the maximum acceptable concentration of cyanide in drink- ing water is 200 μ g / L . Monitoring a mine • You are working in the environmental monitoring lab of a gold mining company. • Every quarter, you collect samples from a series of wells around the mine, as well as surface water (i.e. river and lake) samples from a wider region surrounding the mine....
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- Fall '06
- Chemistry, Upper Saddle River, surface water