A mass of 0.4276 g of ore was dissolved in I−(aq). The resulting solution required 17.98 mL of 0.01043 M Na2S2O3 for complete titration. What is the percentage of copper in the ore?
Express your answer to four significant figures and include the appropriate units.
Thiosulfate solutions are used in iodometric procedures. Iodometric procedures use an iodide solution, I−(aq), to reduce an analyte, such as copper ore:
2 Cu2+(aq) + 5 I−(aq) → 2 CuI(s) + I3−(aq)
The resulting I3− solution is then titrated with a standard solution of Na2S2O3:
I3−(aq) + 2 S2O32−(aq) → S4O62−(aq) + 3 I−(aq)
By keeping track of the amount of thiosulfate added, you can determine the amount of copper present in the ore.
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