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Acid rain is rain or any other form of precipitation that is unusually acidic, meaning that it has elevated levels of hydrogen ions (low pH).Most water, including drinking water, has a neutral pH that exists between 6.5 and 8.5, but acid rain has a pH level lower than this and ranges from 4–5 on average.
Many limestone statues and building surfaces have suffered severe damage due to acid rain. [111] [112] Likewise limestone gravel has been used to protect lakes vulnerable to acid rain, acting as a pH buffering agent. [113] Acid-based cleaning chemicals can also etch limestone, which should only be cleaned with a neutral or mild alkali-based ...
It takes place when rainwater combines with carbon dioxide to form carbonic acid, a weak acid, which dissolves calcium carbonate (limestone) and forms soluble calcium bicarbonate. Despite a slower reaction kinetics , this process is thermodynamically favored at low temperature, because colder water holds more dissolved carbon dioxide gas (due ...
Acid rain: The burning of fossil fuels releases oxides of sulfur and nitrogen into the atmosphere. These react with water in the atmosphere to form sulfuric and nitric acid in rain. Oxidative weathering: Oxidation of some primary minerals, especially sulfides and those containing Fe 2+, generate acidity.
Once the rain reaches the ground, it may pass through soil that provides additional CO 2 produced by soil respiration. Some of the dissolved carbon dioxide reacts with the water to form a weak carbonic acid solution, which dissolves calcium carbonate. [21] The primary reaction sequence in limestone dissolution is the following: [22]
Diagram depicting the sources and cycles of acid rain precipitation. Freshwater acidification occurs when acidic inputs enter a body of fresh water through the weathering of rocks, invasion of acidifying gas (e.g. carbon dioxide), or by the reduction of acid anions, like sulfate and nitrate within a lake, pond, or reservoir. [1]
The inorganic cycle begins with the production of carbonic acid (H 2 CO 3) from rainwater and gaseous carbon dioxide. [6] Due to this process, normal rain has a pH of around 5.6. [ 7 ] Carbonic acid is a weak acid , but over long timescales, it can dissolve silicate rocks (as well as carbonate rocks).
An example is when slaked lime (calcium hydroxide) is mixed into a thick slurry with sand and water to form mortar for building purposes. When the masonry has been laid, the slaked lime in the mortar slowly begins to react with carbon dioxide to form calcium carbonate (limestone) according to the reaction: Ca(OH) 2 + CO 2 → CaCO 3 + H 2 O.