Chapter 10, Problem 88E

A researcher dissolved $1.382\text{g}$ of impure copper in nitric acid to produce a solution of $\text{Cu}{\left({\text{NO}}_{\text{3}}\right)}_{\text{2}}$. The solution went through a series of steps in which $\text{Cu}{\left({\text{NO}}_{\text{3}}\right)}_{\text{2}}$ was changed to $\text{Cu}{\left(\text{OH}\right)}_{\text{2}}$, then to $\text{CuO}$, and then to a solution of ${\text{CuCl}}_{\text{2}}$. This was treated with an excess of a soluble phosphate, precipitating all the copper in the original sample as pure ${\text{Cu}}_3{\left({\text{PO}}_4\right)}_{\text{2}}$. The precipitate was dried and weighed. Is mass was $\text{2}\text{.637}\text{g}$. Find the percentage by mass of copper in the original sample.