Modern European coins contain mixtures of metals - Edexcel - GCSE Chemistry - Question 1 - 2011 - Paper 1

The silver-coloured centre of the 1 euro coin is likely made of a metal such as nickel, while the gold-coloured rim is typically made of an alloy containing metals like copper or zinc. Zinc is often used to give the appearance of gold, which suggests that it is the metal in the rim that contributes to the gold colour.

In pure metals, the atoms are arranged in orderly layers that can easily slide over one another, which makes them soft and malleable. By introducing a second metal into the alloy, the larger atoms disrupt these regular layers. This disruption prevents the layers from sliding easily, thus increasing the overall strength and hardness of the metal. Additionally, the different sized particles create a lock or hold between layers, further enhancing strength.

Iron is extracted from its oxide by heating the oxide with carbon. In this process, the iron oxide is thermally decomposed.

Electrolysis must be used to extract aluminium from its oxide because aluminium oxide has a very high melting point, making it impractical to extract through thermal reduction alone. The electrolysis process allows for the breaking down of the oxide into pure aluminium and oxygen without requiring such high temperatures.