Reference no: EM13211322

A rock sample weighing 1.0637 g (exact to 0.0001 g) was finely ground and the metals were extracted by dissolving in strong acid. The acidic solution was neutralized with base and made up to 250 mL in a volumetric flask. A 20-mL aliquot was treated with 10.00 mL of reducing agent and 10.00 mL buffer and diluted to 50 mL in a volumetric flask. A 20-mL aliquot of the resulting solution was introduced into a separatory funnel along with 10.00 mL of neocuproine solution, and the copper-neocuproine complex was extracted into 20 mL isoamyl alcohol. The absorbance of the alcohol extract measured in a 1.000-cm cell was 0.671. The absorbance of a blank solution prepared in the same manner was 0.025. The molar absorptivity of the copper complex is 7.90 x 103 L.mol?1.cm?1. Calculate the weight percent copper in the rock sample