What type of chemical weathering will dissolve limestone & chemical can be found in limestone rocks & can be easily dissolved when combined with a weak acidic solution?
When carbon dioxide in the air dissolves in rain, a weak carbonic acid is formed. This weak acid, while harmless to plants and animals, is able to dissolve some kinds of rocks, like feldspar and limestone, in a process is carbonation. Carbonic acid is especially reactive with calcite, which is the main mineral that makes up limestone. Over many thousands of years, the dissolving action of carbonic acid on limestone sometimes produces underground caves.
Dissolved carbon dioxide in rainwater or in moist air forms carbonic acid, and this acid reacts with minerals in rocks. The mineral calcite, which is common in limestone, is particularly vulnerable to carbonation. This mineral dissolves in the carbonic acid and gets washed away. Like all metal carbonates, calcium carbonate reacts with acidic solutions to produce carbon dioxide gas. It is this reaction that is responsible for limestone fizzing when dilute hydrochloric acid is placed on its surface. Rainwater with dissolved carbon dioxide in it seeps through soil, where more carbon dioxide is added to the water by plant root systems. The resulting carbonic-acid solution can dissolve limestone and related rocks. Lime and other liming sources such as dolomite reduces soil acidity by neutralizing acid reactions in the soil. The carbonate component reacts with hydrogen ions in the soil solution and in doing so raises the soil pH
This is quite complex dissolution chemistry . There are many textbooks and articles that cover it but these are often very details However a useful overview chapter can be found in Treatise of Geomorphology Epigenetic Weathering in Karstic Environments (2021)
- DOI:10.1016/B978-0-12-818234-5.00218-2
- In book: Reference Module in Earth Systems and Environmental Sciences
A weak acid is one which doesn't ionize fully when it is dissolved in water. Ethanoic acid is a typical weak acid. It reacts with water to produce hydroxonium ions and ethanoate ions, but the back reaction is more successful than the forward one.Unlike strong acids/bases, weak acids and weak bases do not completely dissociate at equilibrium in water, so calculating the pH of these solutions requires consideration of a unique ionization constant and equilibrium concentrations.Weak bases partially ionize in water to produce hydroxide ions. Because the ionization is not complete, the concentration of OH⁻ in a weak base solution is typically much less than the initial base concentration. The Ionization of Weak Acids and Weak Bases. Many acids and bases are weak; that is, they do not ionize fully in aqueous solution. A solution of a weak acid in water is a mixture of the non-ionized acid, hydronium ion, and the conjugate base of the acid, with the non-ionized acid present in the greatest concentration. When carbon dioxide in the air dissolves in rain, a weak carbonic acid is formed. This weak acid, while harmless to plants and animals, is able to dissolve some kinds of rocks, like feldspar and limestone, in a process of carbonation. Limestone is chemically weathered by a process of carbonation. As rainwater absorbs carbon dioxide as it passes through the atmosphere it becomes a weak carbonic acid. The water and carbon dioxide combine to form a weak carbonic acid. This weak carbonic acid acts on the fissures in the limestone. Caves are formed by the dissolution of limestone. Rainwater picks up carbon dioxide from the air and as it percolates through the soil, which turns into a weak acid. This slowly dissolves out the limestone along the joints, bedding planes and fractures, some of which become enlarged enough to form caves.
Dissolution of carbon dioxide from the atmosphere does indeed produce rain that contains carbonic acid. This makes rain acidic normally, with a pH of about 5.5 - 5.7, and this contributes widely to mineral weathering in the environment. However, in many environments, much higher carbon dioxide partial pressures are to be found in the soil, where percolating water adjusts to this greater abundance and becomes even more aggressive toward minerals such as carbonates. Most sub-surface dissolution arises from the gas dissolved as water moves through the soil. When such water drips into caves, where the carbon dioxide partial pressure is lower than in the soil, degassing occurs, the water becomes less aggressive and less able to hold dissolved carbonates. It is this reverse process that is the primary cause of carbonate deposition that forms stalactites and other cave decorations.
Limestone is chemically weathered by a process of carbonation. As rainwater absorbs carbon dioxide as it passes through the atmosphere it becomes a weak carbonic acid. The water and carbon dioxide combine to form a weak carbonic acid. This weak carbonic acid acts on the fissures in the limestone. Limestone is a sedimentary rock made of calcium carbonate usually in the form of calcite or aragonite. It may contain considerable amounts of magnesium carbonate (dolomite) as well Lime is a white solid with strongly basic properties. Lime reacts readily with water to produce slaked lime, which is the chemical compound calcium hydroxide. A considerable amount of heat energy is released during this reaction. When sulfurous, sulfuric, and nitric acids in polluted air and rain react with the calcite in marble and limestone, the calcite dissolves. In exposed areas of buildings and statues, we see roughened surfaces, removal of material, and loss of carved details. Limestone is primarily composed of calcium carbonate (CaCO3) in the form of the mineral calcite. It may also contain other minerals such as dolomite clay minerals, and other impurities. Sometimes, chemical weathering dissolves large portions of limestone or other rock on the surface of the Earth to form a landscape karst. Chemical weathering changes the molecular structure of rocks and soil. For instance, carbon dioxide from the air or soil sometimes combines with water in a process called carbonation. This produces a weak acid, called carbonic acid that can dissolve rock.
Limestone is chemically weathered by a process of carbonation. As rainwater absorbs carbon dioxide as it passes through the atmosphere it becomes a weak carbonic acid. The water and carbon dioxide combine to form a weak carbonic acid. This weak carbonic acid acts on the fissures in the limestone. Limestone is a sedimentary rock made of calcium carbonate usually in the form of calcite or aragonite. It may contain considerable amounts of magnesium carbonate (dolomite) as well Lime is a white solid with strongly basic properties. Lime reacts readily with water to produce slaked lime, which is the chemical compound calcium hydroxide. A considerable amount of heat energy is released during this reaction. When sulfurous, sulfuric, and nitric acids in polluted air and rain react with the calcite in marble and limestone, the calcite dissolves. In exposed areas of buildings and statues, we see roughened surfaces, removal of material, and loss of carved details. Limestone is primarily composed of calcium carbonate (CaCO3) in the form of the mineral calcite. It may also contain other minerals such as dolomite clay minerals, and other impurities. Sometimes, chemical weathering dissolves large portions of limestone or other rock on the surface of the Earth to form a landscape karst. Chemical weathering changes the molecular structure of rocks and soil. For instance, carbon dioxide from the air or soil sometimes combines with water in a process called carbonation. This produces a weak acid, called carbonic acid that can dissolve rock.
- Badges
- Science method
- Similar topics
- Methodology