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Out of \(\mathrm{C}\) and \(\mathrm{CO}\), which is a better reducing agent for \(\mathrm{ZnO}\) ?
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The two reduction reactions are :
\(\mathrm{ZnO}(s)+\mathrm{C}(s) \longrightarrow \mathrm{Zn}(s)+\mathrm{CO}(g)\) ...(i)
\(\mathrm{ZnO}(s)+\mathrm{CO}(g) \longrightarrow \mathrm{Zn}(s)+\mathrm{CO}_2(g)\) ...(ii)
In the first case, there is increase in the magnitude of \(\Delta \mathrm{S}^{\circ}\) while in the second case, it almost remains the same. In other words \(\Delta G^{\circ}\) will have more negative value in the first case when \(\mathrm{C}(s)\) is used as the reducing agent than in the second case when \(\mathrm{CO}(g)\) acts as the reducing agent. Therefore, \(\mathrm{C}(s)\) is a better reducing agent.
\(\mathrm{ZnO}(s)+\mathrm{C}(s) \longrightarrow \mathrm{Zn}(s)+\mathrm{CO}(g)\) ...(i)
\(\mathrm{ZnO}(s)+\mathrm{CO}(g) \longrightarrow \mathrm{Zn}(s)+\mathrm{CO}_2(g)\) ...(ii)
In the first case, there is increase in the magnitude of \(\Delta \mathrm{S}^{\circ}\) while in the second case, it almost remains the same. In other words \(\Delta G^{\circ}\) will have more negative value in the first case when \(\mathrm{C}(s)\) is used as the reducing agent than in the second case when \(\mathrm{CO}(g)\) acts as the reducing agent. Therefore, \(\mathrm{C}(s)\) is a better reducing agent.
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