Copper has been used for thousands of years, either as a pure metal or in alloys

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 1.22 mol Cu. The smelting of copper occurs by the balanced chemical equation: $$ where ?H°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 ?H°fus = 13.0 kJ/mol and a molar heat capacity, cp,Cu = 24.5 J/mol·°C. Find the enthalpy change for the reaction recovering Cu from CuO

Explanation / Answer

PART 1

DH0rxn = (DH0f,Cu+DH0f,CO2)-(DH0f,CO + DH0f,CuO)

         = (0 + -393.5)-(-110.53 + -155)

         = -127.97 Kj

per 1.22 mol Cu , enthalpy change = -127.97*1.22 = -156.1234 kj

PART 2

energy required for melting = Cp,cu*n*DT + n*DHfus

                  = 24.5*1.22*(1084.5-25)+1.22*13.0

                  = 31.68 kj

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