A sample of copper ore of mass 0.4225g was dissolved in acid and the resulting solution of copper(II) reacted with the iodide ion.
2Cu
2+ + 4I
- --> 2CuI + I
2The I
2 produced required 29.96 cm
3 of 0.02100 mol dm
-3 Na
2S
2O
3 solution for complete reaction according to the following equation.
2S
2O
32- + I
2 --> S
4O
62- + 2I
-What was the % by weight of copper in the copper ore?