Copper is an excellent electrical conductor widely used in making electric circuits. 1n

Chapter 3, Problem 3.106

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Copper is an excellent electrical conductor widely used in making electric circuits. 1n producing a printed circuit board for the electronics industry, a layer of copper is laminated on a plastic board. A circuit pattern is then printed on the board using a chemically resistant polymer. The board is then exposed to a chemical bath that reacts with the exposed copper, leaving the desired copper circuit, which has been protected by the overlaying polymer. Finally, a solvent removes the polymer. One reaction used to remove the exposed copper from the circuit board is Cu(s) + Cu(NH3)4Clz(aq) + 4 NH3(aq) -> 2 Cu(NH3)4Cl(aq) A plant needs to produce 5000 circuit boards, each with a surface area measuring 2.0 in. X 3.0 in. The boards are covered with a 0.65-mm layer of copper. 1n subsequent processing, 85% of the copper is removed. Copper has a density of 8.96 g/ cm 3 Calculate the masses of Cu(NH3)4 Clz and NH3 needed to produce the circuit boards, assuming that the reaction used gives a 97% yield.