Question

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

Answer 1

Answer:

Cu2 O is least stable among all so the oxidation reaction of carbon to carbon monoxide may be used to reduce this at lowest temperature.

Explanation:

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