Why is carbon used to extract metals from their oxides?

Carbon is used to extract metals from their oxides because it is a reducing agent that can remove oxygen from the metal oxide.

In more detail, the process of extracting metals from their oxides using carbon is known as reduction. This is a chemical reaction where a substance gains electrons, and in this case, the metal oxide is reduced to the metal. Carbon, being a reducing agent, is able to donate electrons to the metal oxide, causing the oxygen to be removed and the metal to be left behind.

The reason carbon is often used in this process is due to its availability and its ability to form a strong bond with oxygen. When heated, carbon reacts with the oxygen in the metal oxide to form carbon dioxide. This reaction is exothermic, meaning it releases heat, which helps to drive the reaction forward.

For example, in the extraction of iron from its ore, iron(III) oxide (Fe2O3) is reduced by carbon in a blast furnace. The carbon, in the form of coke, is heated to produce carbon monoxide. This carbon monoxide then reacts with the iron(III) oxide to produce iron and carbon dioxide. The overall reaction can be represented as: Fe2O3 + 3CO -> 2Fe + 3CO2.

It's important to note that not all metals can be extracted from their oxides using carbon. Metals that are more reactive than carbon, such as aluminium and potassium, cannot be reduced by carbon and must be extracted using other methods, such as electrolysis. However, for less reactive metals like iron, zinc, and tin, carbon remains a practical and efficient reducing agent for their extraction.