Question

Copper has been used for thousands of years, either as a pure metal or in alloys. It is frequently used today in the production of wires and cables. Copper can be obtained through smelting or recycling. Determine the energy associated with each of these processes in order to recycle 1.43 mol Cu. The smelting of copper occurs by the balanced chemical equation:

CuO(s)+CO(g) -----> Cu(s)+CO2​(g)

where ΔH°f,CuO is = –155 kJ/mol. Assume the process of recycling copper is simplified to just the melting of the solid Cu starting at 25°C. The melting point of Cu is 1084.5°C with ΔH°fus = 13.0 kJ/mol and a molar heat capacity, cP,Cu = 24.5 J/mol·°C. What is the enthalpy change for the reaction recovering Cu from CuO?

Answer 1

CuO(s)+CO(g) -----> Cu(s)+CO2​(g)

DHrxn = (1*DH0F,Cu(S) + 1*DH0F,CO2(g)) - (1*DH0F,CuO(s) + 1*DH0F,CO(g))

      = (1*0 + 1*-393.5)-(1*-155+1*-110.5)

      = -128 Kj/mol

heat required to melt(q) = n*Cp*DT + n*DHfus

                         = 1.43*24.5*(1084.5-25)+1.43*13*10^3

                         = 55.71 kj

total enthalpy change during the process (DH) = n*DHrxn + q

                                              = 1.43*-128 + 55.71

                                              = -127.33 kj