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Chemistry Applications Essay

Sinkholes are one of the most spectacular and wondrous phenomena to happen in nature. Unfortunately though, most sinkholes can cause severe damage through loss of houses, buildings, and even some forms of infrastructure. Sinkholes can greatly vary in size, some spanning over 2,000 feet ,engulfing entire homes, while some are only 3 feet wide acting as a trap for an unsuspecting victim walking by. A misconception by the general public is that we are seeing a hole in the rock when looking at a sinkhole; however, what we actually see when looking at a sinkhole is the soil that was lost inside a void in the rock below. There are a few ways that sinkholes can be formed including erosion from mass amounts of rain, disruption of the soil, or most commonly, chemical changes.  Sinkholes typically form over soluble bedrock such as limestone or other carbonate rocks. These areas are known to be Karst. Karst is by definition layers of soluble rocks that have been eroded by acidic water through the process of dissolution by carbonic acid and sulfuric acid. When rain passes through the atmosphere it collects and dissolves carbon dioxide. The chemical reaction is H2O+CO2~>H2CO3, Carbonic acid. This water then seeps through the soil and then slowly erodes through calcium carbonate (Limestone) and begins to create a void into the rock layers. Another reaction that drastically speeds up the dissolving of the rock below the surface soil is the creation of sulfuric acid, a strong acid. Sulfuric acid is formed when water laden with oxygen forms together with sulfide (H2S) in the ground. The reaction goes as followed: H2S+2O2 ~> H2SO4, Sulfuric Acid. These corrosive acids then dissolve the rock below the surface soil until the rock can no longer hold the amount of pressure exerted by the soil above. Once the now weak layer of the rock gives out, soil quickly funnels down into the rock into the space that was caused from deterioration by the acids until it is completely filled. The result of this action can be a huge hole in the earth’s surface or simply a very small innocent hole, depending on how much damage was done to the rock below.