Water plays an important role in chemical weathering class 9
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Answer:
Explanation:
Water plays a very important role in chemical weathering in three different ways. First, it combines with carbon dioxide in the soil to form a weak acid called carbonic acid. Microbe respiration generates abundant soil carbon dioxide, and rainwater (also containing atmospheric carbon dioxide) percolating through the soil provides the water. Carbonic acid slowly dissolves away minerals in rock, especially the carbonate minerals that make up limestone and marble. The weak acid decomposes the insoluble rock into watersoluble products that move into the groundwater. In high concentrations, these dissolved minerals can cause the water to be considered "hard."
Second, water can hydrate minerals by being adsorbed onto the mineral lattice. The conversion of anhydrite into gypsum is an example.
Finally, the water can break up minerals through hydrolysis . The most common group of minerals, the silicates, is decomposed by this process. Reactive hydrogen ions that are liberated from the water attack the crystal lattice, and the mineral decomposes.
Other agents of chemical weathering are gases and acids. Oxygen combines with the metals in minerals to form oxides such as hematite, limonite, and goethite. They are just like the rust that forms on metal exposed to rain or moisture. Air pollution that contributes to weathering of rock generally contains weak concentrations of strong acids such as sulfuric and nitric acid. Strong acids escaping from steam vents around volcanoes and abandoned mine sites can also contribute to increased weathering of nearby rocks.
Answer:
Water plays a very important role in chemical weathering in three different ways. First, it combines with carbon dioxide in the soil to form a weak acid called carbonic acid. ... Finally, the water can break up minerals through hydrolysis . The most common group of minerals, the silicates, is decomposed by this process.
Explanation:Weathering is the breaking down of rocks, soils, and minerals as well as wood and artificial materials through contact with the Earth's atmosphere, water, and biological organisms. Weathering occurs in situ (i.e., on site, without displacement), that is, in the same place, with little or no movement, and thus should not be confused with erosion, which involves the transport of rocks and minerals by agents such as water, ice, snow, wind, waves and gravity and then being transported and deposited in other locations.
Two important classifications of weathering processes exist – physical and chemical weathering; each sometimes involves a biological component. Mechanical or physical weathering involves the breakdown of rocks and soils through direct contact with atmospheric conditions, such as heat, water, ice and pressure. The second classification, chemical weathering, involves the direct effect of atmospheric chemicals or biologically produced chemicals also known as biological weathering in the breakdown of rocks, soils and minerals.[1] While physical weathering is accentuated in very cold or very dry environments, chemical reactions are most intense where the climate is wet and hot. However, both types of weathering occur together, and each tends to accelerate the other. For example, physical abrasion (rubbing together) decreases the size of particles and therefore increases their surface area, making them more susceptible to chemical reactions. The various agents act in concert to convert primary minerals (feldspars and micas) to secondary minerals (clays and carbonates) and release plant nutrient elements in soluble forms.
The materials left over after the rock breaks down combined with organic material creates soil. The mineral content of the soil is determined by the parent material; thus, a soil derived from a single rock type can often be deficient in one or more minerals needed for good fertility, while a soil weathered from a mix of rock types (as in glacial, aeolian or alluvial sediments) often makes more fertile soil. In addition, many of Earth's landforms and landscapes are the result of weathering processes combined with erosion and re-deposition.Mineral hydration is a form of chemical weathering that involves the rigid attachment of H+ and OH- ions to the atoms and molecules of a mineral.
When rock minerals take up water, the increased volume creates physical stresses within the rock. For example, iron oxides are converted to iron hydroxides and the hydration of anhydrite forms gypsum.