The concept of `DeltaG^@` of coupled reaction are used explain reductions in metallurgy. Explain the above statement.

Answer

For a process to be spontaneous, `DeltaG^@` of the process should be negative. A process with positive `DeltaG^@` can be made to take place spontaneously by coupling it with another process with large negative `DeltaG^@`. In such coupled reaction, the net `DeltaG^@` becomes negative.