A metal alloy, known to contain only the metals copper, zinc, and lead, is subjected to the following analysis: A 2.4505g sample of the alloy is dissolved in concentrated nitric acid and the solution diluted to 500.0mL. A 250.0mL aliquot is then treated with dilute sulfuric acid and the resulting lead sulfate collected, dried and weighed, 0.0531g being obtained. The remainder of the solution is mixed with an excess of sodium hydroxide. The resulting solid is then heated to convert the hydroxide solid into an oxide which is then collected, dried, and weighed as copper(II) oxide, 1.3618g being obtained.
A) Calculate the % of the metals present in the alloy.
B) What volume of 3.0M sodium hydroxide must be added to the second portion in order to assure a 50% excess of sodium hydroxide? Why is this excess necessary?