Copper in an alloy is estimated by dissolving in conc. Nitric acid . In this process copper is converted to cupric nitrate with the evolution of nitric oxide (NO) . The misture when treated with potassium iodide forms cupric iodide. Which is unstable and decomposes to cuprous iodide and iodine.The amount of copper in the alloy is estimated by litrating the libereated iodine with sodium thiosulphate. The reactions are
a `Cu + b HNO_(3) rarr c Cu(NO_(3))_(2)+d NO + e H_(2)O`
f `Cu l_(2) rarr g Cu_(2)I_(2) + h I_(2)`
i `Na_(2)S_(2)O_(3)+ hat (j) I_(2) rarr k Na_(2)S_(4)O_(6)+lNaI`
(fill up the blanks)
(a) The coefficients are : a = __________ . b = _________ , c = ___________ , d = __________ and e =_________ .
(b) The coefficients are : f = _________ , g = _________ and h = ________.
(c) The coefficients are : i = ________ , j = ___________ , k = and l = ________.
(d) If 2.54 g of `I_(2)` is evolved from a 2.0 g sample of the alloy, what is the percentage of copper in the alloy ?
(atomic, weight of iodine and coper are 127 and 63.5, respectively )