Calcium carbonate reaction with acid rain

A marble statue is being slowly dissolved by reaction of calcium carbonate with acid rain (top). A researcher examines tree branches damaged by acid rain on Mount Mitchell in North Carolina (bottom). 

To illustrate the effect of ionic strength on degradation of calcium carbonate we have calculated the solubility of calcium carbonate in deionized water, acid at pH = 4.0 and acid rain at pH = 4.0 with an ionic strength of 7.2 x 10 in the absence of CO2. The results of these calculations are shown in Table 2 and are plotted in Figure 3. These data show that the ionic strength contribution of sea spray and other atmospheric sources are as significant as the neutralization reaction with acid at pH = 4.0 in the degradation of coquina by acid rainfall. 

One of the harmful effects of acid rain is its reaction with structures made of limestone, which include marble structures, ancient ruins, and many famous statues (Fig. 8.19). Write the equation you would expect for the reaction between acid rain, which contains sulfuric acid, and limestone, solid calcium carbonate. Write a second equation with the same reactants, showing that the expected but unstable carbonic acid decomposes to carbon dioxide and water. 

As mentioned earlier, pH changes occur from pollution stresses such as acid rain or mine runoff of from geochemical reactions such as dissolution of calcium carbonate. In acidified regions, species diversity and population density drop dramatically with some lakes and streams becoming devoid of life. Changes in metal complexes occur both naturally and biologically, with direct and indirect effects on ligand concentration and complex stability. 

Write reactions to show how nitric and sulfuric acids are produced in the atmosphere. Write reactions to show how the nitric and sulfuric acids in acid rain react with marble and limestone. (Both marble and limestone are primarily calcium carbonate.)... 

One harmful effect of acid rain is the deterioration of structures and statues made of marble or limestone, both of which are essentially calcium carbonate. The reaction of calcium carbonate with sulfuric acid yields carbon dioxide, water, and calcium sulfate. Because calcium sulfate is marginally soluble in water, part of the object is washed away by the rain. Write a balanced chemical equation for the reaction of sulfuric acid with calcium carbonate. 

In this paper, we describe an onsite weathering experiment designed to identify acid-rain increased dissolution of carbonate rock. This experiment is based on the measurement of the change in rainfall-runoff composition from the interaction of a rock surface with incident acid rain 2. The experiment involves conducting long-term exposures of two commercially and culturally important calcium carbonate dimension stones (i.e., Indiana Limestone (commercial name for Salem Limestone) and Vermont Marble (commercial name for Shelburne Marble)) (3-5). This technique appears to give a direct measurement of the chemical dissolution of carbonate rock from the combined reactions of wet and dry deposition. Preliminary results from the initial months of onsite operation are presented to illustrate the technique. 

Calcium carbonate is the major component of limestone and marble. Sulfuric acid is one of the major components of acid rain. Write a balanced chemical reaction that shows how sulfuric acid reacts with calcium carbonate. 

Chemically speaking, limestone is calcium carbonate. Although calcium carbonate is insoluble in water, it does dissolve in a weakly acidic solution. Surface water is weakly acidic, because carbon dioxide in the air dissolves in rain and reacts with the water to form carbonic acid. As the acidic surface water percolates through the ground, it converts insoluble calcium carbonate to soluble calcium hydrogen carbonate. When we heat water, we reverse this reaction, causing deposits of what amounts to limestone to build. 

Thus, a gas is given off when CaC03(s) reacts with an acid and dissolves. The reaction represented by equation (5.16) is responsible for the erosion of marble statues by acid rain, such as the one shown in Figure 5-11. Equation (5.16) also shows that CaC03(s) has the ability to neutralize acids. Not surprisingly, calcium carbonate, like magnesium hydroxide, is used as an antacid. 

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