Extracting Metals – GCSE Chemistry

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Introduction

  • Metals are shiny, strong and good conductor of heat and electricity making them useful for tools, wires, and structures.
  • Metals are naturally found in the Earth’s crust combined with other elements in mineral deposits called ores, which are then extracted through mining and refined for use.
  • Some common metals:

Periodic table tiles showing iron, aluminium and copper for extracting metals comparison.

Daily-life examples where metals are used:

Images of common metal products including frying pan, jewellery, wires, pipes, car body and soda can to show uses of extracted metals.

The Reactivity Series of Metals

  • Reactivity is the ability of a substance, especially a metal, to undergo a chemical reaction with other substances like water, acids, or oxygen.
  • It shows how easily a metal can lose electrons to form positive ions.
  • If a metal reacts quickly, it is highly reactive.
  • If it reacts slowly or not at all, it is less reactive or unreactive.

Reactivity Series of Metals:

  • The reactivity series is a list of metals that shows how easily different metals react.
  • It is arranged in order of their reactivity, from most to least reactive.
  • A common series is:

Reactivity series chart showing metals from most reactive to least reactive for GCSE chemistry.

Extraction of Metals:

Table showing methods of metal extraction including electrolysis, reduction by carbon and reduction by hydrogen or found native.

What are Oxidation and Reduction?

  • Oxidation and reduction are the reactions which always happen together in a redox reaction.
  • They involve moving electrons from one substance to another.

Oxidation

  • Oxidation is the gain of oxygen by a substance or the loss of electrons during a reaction.

Diagram showing magnesium reacting with oxygen to form magnesium oxide in an oxidation reaction.

Where:

    • Mg = Magnesium
    • O = Oxygen

Reduction

  • Reduction is the loss of oxygen by a substance or the gain of electrons during a reaction.

Reduction reaction showing extracting metals: magnesium oxide breaking down into magnesium and oxygen.

Where:

    • Mg = Magnesium
    • O = Oxygen

How are Oxidation and Reduction used to Extract Metals?

  • Most metals are found in nature combined with oxygen or other elements, not as pure metals.
  • To get the pure metal, we need to remove the oxygen from these compounds.
  • This is done using a process called reduction.
  • In simple words, reduction helps us take away oxygen, so we get the pure metal we need.
  • We can use carbon or hydrogen as reducing agents to take away the oxygen.

Extraction of Metals from Oxides using Carbon:

  • Metals below carbon in the reactivity series are – zinc, iron, lead, copper and these metals can be extracted from their oxides using carbon.
  • Carbon removes oxygen from the metal oxide to form pure metal, while carbon itself gets oxidised to carbon dioxide.

Examples:

Carbon reduction equations used in extracting metals, showing removal of oxygen from iron oxide, zinc oxide, and lead oxide.

Extraction of Metals from Oxides using Hydrogen:

  • Metals below hydrogen in the reactivity series are – copper, silver etc. are less reactive and so these metals can be extracted from their oxides using hydrogen.
  • Hydrogen removes oxygen from the metal oxide to form pure metal, while hydrogen itself is oxidised to water.

Examples:

Hydrogen reduction equations used in extracting metals, showing hydrogen reducing copper oxide, tungsten oxide and lead oxide to form pure metals and water.

For Highly Reactive Metals:

  • Metals like aluminium and sodium are very reactive, so they are high up in the reactivity series.
  • They form strong bonds with oxygen, making very stable compounds.
  • Carbon is not reactive enough to remove the oxygen from these metals, so we cannot use carbon to extract them.
  • We need to use other methods like electrolysis to get these metals

Note: To Learn about Electrolysis, please tap on the link: Electrolytic processes

What Are The Methods of Preventing Rusting?

  • There are different methods we can use to prevent rusting. Here they are:

Painting and Plastic Coating

  • A layer of paint or plastic is used on car bodies, fences, etc., which keeps out air and water.

Oiling or Greasing

  • It is commonly used for machine parts and bicycle chains.
  • The oil prevents water and oxygen from reaching the metal.

Galvanising

  • When iron is coated with a layer of zinc, it is called galvanising.
  • The zinc protects the iron by forming a barrier, and even if it is scratched, zinc reacts more easily than iron, so it prevents rusting.

Electroplating

  • Using electricity, a thin layer of another metal such as chromium or silver is coated onto iron or steel.
  • This protects it from rust and also makes it look better.

Alloying

  • When iron is mixed with other metals, such as chromium and nickel, it makes stainless steel.
  • This process is called alloying, and the steel does not rust easily, so it is used in cutlery, sinks, and medical tools.

Frequently Asked Questions

Solution:

It is a list of metals arranged from most reactive to least reactive, helping us understand how metals react with water, air, acids, and how they are extracted.

Solution:

Because metals react with oxygen in air, forming stable metal oxides over time.

Solution:

Less reactive metals (like iron, zinc, lead, copper) are extracted from their oxides using carbon or hydrogen, which remove oxygen from the metal oxide (reduction).

Solution:

Highly reactive metals (like aluminium, sodium, potassium) are extracted using electrolysis, as they are too reactive for carbon to reduce their oxides.

Solution:

When a metal gains oxygen or loses electrons during a reaction.

Solution:

When a metal loses oxygen or gains electrons during a reaction, usually when extracting metals from their oxides.

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