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VOLCANOES AND GAS LAWS

VOLCANOES AND GAS LAWS. WHAT ARE VOLCANOES. A VOLCANO REFERS TO THE OPENING IN THE EARTH’S CRUST THROUGH WHICH MOLTEN ROCK, GASES , AND ASH ERUPT AND THE LANDFORM THAT DEVELOPS AROUND IT. The eruption of Mt. St. Helens on M ay 18, 1980. FORMATION OF VOLCANOES EMITTING GASES.

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VOLCANOES AND GAS LAWS

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  1. VOLCANOES AND GAS LAWS

  2. WHAT ARE VOLCANOES A VOLCANO REFERS TO THE OPENING IN THE EARTH’S CRUST THROUGH WHICH MOLTEN ROCK, GASES, AND ASH ERUPT AND THE LANDFORM THAT DEVELOPS AROUND IT. The eruption of Mt. St. Helens on May 18, 1980.

  3. FORMATION OF VOLCANOES EMITTING GASES GASES SUCH AS CARBON DIOXIDE, SULPHUR DIOXIDE AND WATER VAPOUR ARE TRAPPED WITHIN THE EARTH – DISSOLVED IN MAGMA AND ARE AT EXTREME TEMPERATURE AND PRESSURE. THESE GASES TRAPPED IN MAGMA TRAVEL UPWARDS THROUGH CRACKS, VENTS AND OTHER WEAK SPOTS IN THE ROCKS TO THE EARTH SURFACE FORMING A VOLCANO. BUT IF THE PATH IS BLOCKED, THE GASES CANNOT ESCAPE EASILY AND PRESSURE BUILDS UP AGAINST THE THIN ROCK LAYER AT THE EARTH’S SURFACE. ULTIMATELY IT GIVES WAY, CAUSING THE GAS TO EXPAND RAPIDLY, OFTEN IN A DRAMATIC EXPLOSION. EXPLOSIVE VOLCANOES ARE USUALLY ASSOCIATED WITH RHYOLITIC MAGMA, WHICH ARE HIGH IN SILICA AND GAS CONTENT AND RESIST FLOW.

  4. Lower temperature, lower pressure, increased volume Rocks which blocked the mouth is now shattered by pressure exerted by gases Pressure is released Even higher pressure and temperature Lower volume High temperature Trapped gases Higher volume

  5. VOLCANOES AND GAS LAWS THE COMBINED GAS LAW CAN BE APPLIED TO VOLCANOES, WHICH IS A COMBINATION OF BOYLE’S LAW, CHARLE’S LAW AND GAY LUSSAC’S LAW. IN THE EARTH’S MANTLE - LARGER VOLUME - HIGH PRESSURE - HIGH TEMPERATURE BEFORE ERUPTING (THE VENT BLOCKED BY THIN ROCK LAYER) - LESS VOLUME - HIGHER PRESSURE - HIGHER TEMPERATURE

  6. GAS LAWS INSIDE THE VOLCANO THE MANTLE MAKES UP 80% OF THE EARTH’S TOTAL VOLUME. SINCE PRESSURE IS INVERSELY PROPORTIONAL TO VOLUME, AS VOLUME INCREASES, THE PRESSURE DECREASES (BOYLE’S LAW). SO IN THE MANTLE THE PRESSURE EXERTED BY THE GASES IS RELATIVELY LESS AS VOLUME IS MORE. ALSO TEMPERATURE IS RELATIVELY LESS IN THE MANTLE, SINCE PRESSURE IS LESS AND TEMPERATURE IS DIRECTLY PROPORTIONAL TO PRESSURE (GAY – LUSSAC’S LAW). WHEN THE MAGMA, CONTAINING TRAPPED GASES RISE UP THROUGH THE WEAK SPOTS OR CRACKS IN THE EARTH’S CRUST, THE VOLUME DECREASES WHEREAS PRESSURE AND TEMPERATURE INCREASES BECAUSE OF MORE COLLISIONS BETWEEN GAS MOLECULES (KINETIC MOLECULAR THEORY). ULTIMATELY THE PRESSURE INSIDE THE CLOSED VENT OF THE VOLCANO BECOMES SO GREAT THAT THE ROCKS BLOCKING THE MOUTH OF THE VOLCANO GIVES WAY. THE GASES WHICH ARE AT A HIGH TEMPERATURE AND PRESSURE INSIDE THE VENT, EXPANDS WITH EXPLOSIVE FORCE WHEN THEY AREEXPOSED TO ATMOSPHERIC PRESSURE AT THE EARTH’S SURFACE CAUSING AN EXPLOSIVE VOLCANIC ERUPTION.

  7. GAS LAWS OUTSIDE THE VOLCANO THE GASES INSIDE THE VENT ARE AT A VERY HIGH PRESSURE AND TEMPERATURE AND LOWER VOLUME. SINCE VOLUME IS INVERSELY PROPORTIONAL TO PRESSURE (BOYLES LAW) WHEN THE GASES COME OUT FROM THE VENT, PRESSURE DECREASES AND THE VOLUME INCREASES. ALSO WHEN PRESSURE DECREASES THE TEMPERATURE DROPS, AS PRESSURE AND TEMPERATURE ARE DIRECTLY PROPORTIONAL (GAY – LUSSAC’S LAW). THIS SUDDEN CHANGE IN PRESSURE, VOLUME AND TEMPERATURE CAUSES THE GASES TO EXPAND WITH EXPLOSIVE FORCE AND THUS SHATTERING ROCKS INTO FINE DUST.

  8. Mt. St. Helens • Mt. St. Helens is an example of an explosive volcano. • It is located in Skamania County, Washington, in United States of America. • It last exploded on May 18, 1980.

  9. RESULTS OF THE EXPLOSION • FIFTY SEVEN PEOPLE DIED • 7000 ANIMALS GOT KILLED • 12 MILLION FISH GOT KILLED • 250 HOMES WERE DESTROYED • 47 BRIDGES WERE DESTROYED • 24 KM OF RAILWAY LINE AND 298 KM HIGHWAY WERE DESTROYED • ELEVATION OF MOUNTAIN WAS REDUCED AND MASSIVE LANDSLIDE • OCCURED • HUGE SECTION OF FOREST GOT DESTROYED

  10. MORE RESULTS OF THE EXPLOSION THAT WAS NOT ALL. SEVERAL TOWNS WERE DESTROYED. NEARBY TOWNS AND CITIES WERE COVERED WITH ASH. POISONOUS GASES LIKE SULPHUR DIOXIDE WERE RELEASED INTO THE ATMOSPHERE AND RESULTED IN ACID RAIN. MANY PEOPLE HAD TO MOVE PERMANENTLY. THOUSANDS OF ECOSYSTEMS WERE AFFECTED. THE DUST ROSE 16 KM HIGH AND COVERED THE AREA, TURNING DAY INTO NIGHT AND REDUCING TEMPERATURES BY BLOCKING AND REFLECTING SUNLIGHT. MANY INDUSTRIES WERE AFFECTED LIKE FISHING, FARMING AND LUMBER. FOOD CHAINS AND HABITATS CHANGED, AND MANY ANIMALS DIED LATER ON. MOREOVER THE ERUPTION OF MOUNT ST. HELENS AFFECTED ALL.

  11. WORK CITED: - Kessel, F. ;., Davies, H. ;., Lantz, L. ;., Thomas, O. ;., Tompkins, P. ;., & Jenkins, D. (2001). Nelson Chemistry 11. Canada: Nelson Thomson Learning. Millennium Ark: Hot News. (n.d.). Retrieved May 28, 2009, from <http://standeyo.com/NEWS/07_Earth_Changes/071228.volcano.dangers.html> Mount St. Helens - Wikipedia, the free encyclopedia. (n.d.). Retrieved May 28, 2009, from <http://en.wikipedia.org/wiki/Mount_St._Helens> Namowitz, S. N., & Spaulding, N. E. (2004). Earth Science. United States of America: Mcdougal Littell. The Smallest Clues. (n.d.). Retrieved May 28, 2009, from <http://minerals.cr.usgs.gov/gips/na/small.html> Types Of Eruptions - Volcanoes - Forces of Nature. (n.d.). Retrieved May 28, 2009, from <http://library.thinkquest.org/C003603/english/volcanoes/typesoferuptions.shtml> Wired | BoomTown | AllThingsD. (n.d.). Retrieved May 28, 2009, from <http://kara.allthingsd.com/tag/wired/>

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