Reactivity Series: An Overview

• Most metals are not found in a pure state but rather in the form of ores, which are combinations of metals with other elements.
• The ability of a metal to react, its reactivity, can be compared and ranked on a reactivity series.
• The reactivity series from most to least reactive is usually given as Potassium, Sodium, Calcium, Magnesium, Aluminium, Carbon, Zinc, Iron, Lead, Copper, Silver, Gold.
• The more reactive a metal is, the more likely it is to form compounds with other elements, therefore, it’s more frequently found in ores.
• Less reactive metals can be found in their pure, uncombined state. These include gold and platinum.

Extraction of Metals from Ores

• The type of extraction used depends on the metal's position in the reactivity series.
• For metals higher than carbon in the reactivity series, we primarily use electrolysis for extraction. This process requires large amounts of electric current and is costly.
• For metals below carbon in the reactivity series, extraction happens with the help of carbon in form of coke. Such metals can be reduced by heating with carbon; this removes the oxygen from the ore, leaving the metal.
• For instance, Aluminium is extracted from Bauxite via electrolysis, while Iron is extracted from its ore, hematite, in a blast furnace with coke.

Role of Blast Furnaces

• A blast furnace is a type of metallurgical furnace used for smelting to produce industrial metals, generally pig iron.
• The furnace is charged with the iron ore, coke and limestone. The coke is the reducing agent, and the limestone removes impurities.
• The hot air blown into the blast furnace burns the coke, which produces carbon dioxide that reacts with the unburned coke to produce carbon monoxide. This then reduces the iron ore to Iron.

Environmental Impacts

• Mining and extracting metals has a significant impact on the environment. It contributes to land degradation, loss of biodiversity, erosion, and contamination of surface water, groundwater, and soil.
• The process of metal extraction is energy intensive and contributes to climate change through the release of carbon dioxide.
• Research and investment are therefore focused on sustainable and environmentally friendly methods of extracting metals.

Key Points for Metal Extraction

• Remember that metals above carbon in the reactivity series must be extracted using electrolysis, while those below can be extracted using carbon.
• The process of extraction has significant environmental impacts, making research into sustainable extraction methods important.
• Understanding the concept of a reactivity series (including the ability to predict reactivity) is crucial for understanding how and why different methods are used to extract metals.