Extracting Metals

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:

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.

• 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:

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

Where:

• • Mg = Magnesium
  • O = Oxygen

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

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.

• 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.

• 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.

• 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

What Are The Methods of Preventing Rusting?

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

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

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

• 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.

• 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.

• 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