Question

According to Ellingham diagram the oxidation reaction of carbon to carbon monoxide may be used to reduce which of the following oxides at the lower temperature?
a) MgO
b) ZnO
c) Al2O3
d) Cu2O

Answer 1

C will act as a reducing agent for reduction of Cuprous oxide to Cu +1 with the removal of oxygen as ∆G is less than 0.

2Cu2O --------> 4 Cu + O2                    ∆G = 300 Kilo Joule / mole  

C + O2 ---------> CO2                             ∆G = -350 Kilo Joule / mole

 

If we coupled above two reactions,

2 Cu2O + C + O2 ---------> 4Cu + O2 + CO2     ∆G =300 + (-350)  

2 Cu2O + C ------> 4Cu + CO2                              ∆G = - 50 Kilo Joule/ mole

Answer 2

Answer:

d) Cu2O

Explanation:

Cu 2 O is least stable among all so the oxidation reaction of carbon to carbon monoxide may be used to reduce this at lowest temperature.