Stoichiometry question... Please help?

Question

1. In the production of printed circuit boards for the electronics industry, a 0.60mm layer of copper is laminated onto an insulating plastic board. Next, a circuit pattern made of a chemically resistant polymer is printed on the board. The unwanted copper is removed by chemical etching, and the protective polymer is finally removed by solvents. One etching reaction is:

Cu(NH3)4Cl2 + 4NH3 + Cu --> 2Cu(NH3)4Cl.

A plant needs to manufacture 10,000 printed circuit boards, each 8.0 x 16.0cm in area. An average of 80% of the copper is removed from each board (density of copper = 8.96g/cm3). What masses of Cu(NH3)4Cl2 and NH3 are needed to do this? Assume 100% yield.

thanks for any help.

Answer 1

boards * (mass Cu/board) * atomic wt = total mol Cu

=10,000 boards * [(80/100) * (8.0*16*0.060)cm3 * (8.96gCu/cm3)]/board * (1molCu/63.546g) = 8663 mol Cu

Cu(NH3)4Cl2:

8663molCu * (1mol Cu(NH3)4Cl2 / 1mol Cu) * (mol wt. of Cu(NH3)4Cl2) = x*x

NH3

8663molCu * (4mol NH3 / 1mol Cu) * (mol wt. of NH3) = yyy