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 1.32 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, c_P,Cu = 24.5 J/mol·°C.

Part 1: Enthalpy change for the reaction recovering Cu from CuO = ____KJ

Part 2: Energy for recycling Cu = ____ kJ

Answer 1

ΔΗ° = Σn_pΔΗ°_(product) - Σn_rΔΗ°_p(reactant)

= [ (n_(cu)  ΔΗ°_f(cu) ​​​) + ( n_(co2) ΔΗ°f _(co2) ​​​​​) - [ n_(CuO)  ΔΗ°_f(CuO) ​​​​​​] + [ n_(co) ΔΗ°_f(co)]  

= [(0) + ( - 393.50 kJ/mol )] - [(-155 kJ/mol ) + (-110.52 kJ/mol)

= -127.98 kJ/mol

ΔΗ° for recovering 1.32 mol Cu = (1.32 mol) (-127.98 kJ/mol) = -168.9336 kJ

Hence, enthalpy change for the reaction recovering 1.32 mol Cu is -168.9336 kJ

PART-2 :- Recycling:

i) convert solid Cu to liquid Cu at 25°C:
q₁ = n ∆H°fus
= (1.32moles) x (13.0 kJ/mol)
= 17.16 kJ = 17.2 KJ

ii) Heat liquid Cu at 25°C to liquid Cu at 1084.5°C :
q₂ = n cp ∆T
= (1.32 mol) x (24.5 J/mol•°C) x (1084.5°C - 25°C)
= 34,264.23 J

= 34.26423KJ = 34.3 KJ

Total energy associated with recycling process:-

= (17.2 + 34.3) kJ
= 51.5 KJ