Metals have many uses - Edexcel - GCSE Chemistry - Question 3 - 2012 - Paper 1

Iron is extracted from its ore, usually haematite (Fe₂O₃), through a process called reduction. This typically occurs in a blast furnace where the ore is heated with carbon (coke) and limestone. The carbon reacts with the oxygen in the ore, reducing it to iron and producing carbon dioxide as a byproduct. The reaction can be summarized as:

$\text{Fe}_2\text{O}_3 + 3\text{C} \rightarrow 2\text{Fe} + 3\text{CO}$

The molten iron is collected and can then be further processed.

In the reaction between copper oxide and hydrogen, oxidation and reduction occur simultaneously. Copper oxide (CuO) is reduced as it loses oxygen to form copper (Cu). The hydrogen gas (H₂) is oxidized as it gains oxygen to form water (H₂O). Thus, the CuO loses oxygen and is reduced, while H₂ gains oxygen and is oxidized.

Shape memory alloys are advantageous for spectacle frames because they can return to their original shape after being deformed. This property allows them to withstand bending and twisting, maintaining their functionality and fit without sustaining damage. In contrast, most other alloys remain deformed after bending, affecting their usability and lifespan.

Alloys are usually stronger than the pure metals from which they are made because they have stronger bonds between the molecules they contain.