A 0.4713 g sample of pewter, containing tin, lead, copper, andzinc, was dissolved in acid. Tin was precipitated as SnO2·4H2O andremoved by filtration. The resulting filtrate and washings werediluted to a total volume of 250.0 mL. A 15.00 mL aliquot of thissolution was buffered, and titration of the lead, copper, and zincin solution required 35.63 mL of 0.001504 M EDTA. Thiosulfate wasused to mask the copper in a second 20.00 mL aliquot. Titration ofthe lead and zinc in this aliquot required 34.75 mL of the EDTAsolution. Finally, cyanide was used to mask the copper and the zincin a third 25.00 mL aliquot. Titration of the lead in this aliquotrequired 26.61 mL of the EDTA solution. Determine the percentcomposition by mass of each metal in the pewter sample.
