Powerful chemical reactions drive volcanic eruptions.
An erupting volcano is a sight to behold. These dramatic geological events are spectacular displays of chemical reactions going on beneath the earth's surface. So explosive is the reaction that science students from grade school on up are fascinated with other, less harmful chemical reactions that mimic volcanic explosions. Find out more about what goes on below the surface chemically when a volcano erupts.
Volcanoes Explained
Volcanoes are geological formations with fissures or channels that lead deep into the molten lava core of the earth. The fissures in a volcano are filled with magma, or molten rock that is so hot that it flows like liquid fire burning everything in its path. When heat and pressure build up to a great extent inside of the volcano, the magma melts the rock holding it in and pushes out of these fissures and into the volcano. It erupts out of the top of the volcano and flows down its sides as lava.
Magma
Magma is filled with dissolved gases. When a volcano erupts, these gasses are released into the earth's atmosphere. Deep below the earth's surface, near its core, the gasses inside of magma are dissolved in molten rock. When the rock melts, magma moves upward where there is less pressure to hold them intact.
Pressure
Near the surface, pressure is lower than it is near its core, where pressure is greater. As pressure levels decrease, tiny bubbles are able to form in the gases inside of magma. These bubbles take up space, or volume in the magma. As the bubbles increase, the rock containing the magma begins to give way. That is because more bubbles make the magma less dense that the rock surrounding it. As the magma becomes less dense due to less pressure and more bubbles, it is able to move upward toward the surface.
Eruption and Gasses Released
A volcanic eruption occurs when a chemical reaction involving volume, pressure and gas occurs. As volcanic gases approach the surface, they increase in volume drastically. Water vapor comprises the largest amount of volcanic gases in magma. Other gases include carbon dioxide, sulfur dioxide, hydrogen sulfide, hydrogen, carbon monoxide, hydrogen chloride and helium. When these gases increase in volume, they can no longer be contained by the volcanic rock and they burst forth into the atmosphere where prevailing winds carry them away. Sulfur dioxide, carbon dioxide and hydrogen fluoride can be dangerous when released. For example, sulfur dioxide can lead to acid rain, which pollutes the area surrounding the volcano. Carbon dioxide sinks down and settles into ground where it can contaminate soil and water sources, harming the people and animals that consume them.
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