When can carbon reduce a metal oxide to the metal?

When can carbon reduce a metal oxide to the metal?

• A. If the metal is more reactive than carbon.
• B. If the metal has a higher atomic number than carbon.
• C. If the metal is less reactive than carbon.
• D. Only for noble metals.

Answer: (C)

Reducing power comes from where a metal sits in the reactivity scale. Carbon can take oxygen away from a metal oxide only if the metal is less reactive than carbon. When a metal oxide is heated with carbon, carbon acts as the reducing agent and the metal is formed while carbon is oxidized to carbon monoxide or carbon dioxide. Metals that are more reactive than carbon won’t be reduced in this way under ordinary conditions, which is why carbon can extract metals like iron, copper, or zinc but not aluminum or magnesium. Noble metals aren’t singled out here; the key idea is the metal’s reactivity relative to carbon.

Reducing power comes from where a metal sits in the reactivity scale. Carbon can take oxygen away from a metal oxide only if the metal is less reactive than carbon. When a metal oxide is heated with carbon, carbon acts as the reducing agent and the metal is formed while carbon is oxidized to carbon monoxide or carbon dioxide. Metals that are more reactive than carbon won’t be reduced in this way under ordinary conditions, which is why carbon can extract metals like iron, copper, or zinc but not aluminum or magnesium. Noble metals aren’t singled out here; the key idea is the metal’s reactivity relative to carbon.