In the production of printed circuit boards for the electronics industry, a 0.55

Question

In the production of printed circuit boards for the electronics industry, a 0.555 mm 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(aq) + 4NH3(aq) + Cu(s) ? 2Cu(NH3)4Cl(aq)

A plant needs to manufacture 10600 printed circuit boards, each 8.20cm x 17.0cm in area. An average of 92.0% of the copper is removed from each board (density of copper=8.96g/cm3.) What mass of Cu(NH3)4Cl2 reagent is required?

Explanation / Answer

total volume of copper being rmoved is .555 *10^-1 * 8.20 * 17 *.92 *10600 = 75448.3 cm^3

mass of copper being rmoved = 75448.3 * 8.96 = 676016 grams .

moles of copper = 676016/molecular weight of copper =676016 / 63.5 =moles

one mole of copper needs one mole of Cu(NH3)4Cl2.. so we need 10645.9 moles of Cu(NH3)4Cl2 .\

for this we need a mass of Cu(NH3)4Cl2 = moles * molar mass =10645.9* 202.575 =2156593.19 grams = 2156.6 kgs

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