Limestone solubility

Rainwater for instance will pick up atmospheric COg and react with calcium carbonate (limestone) to form a soluble substance, calcium bicarbonate. This reaction gives water its natural hardness . 

In the geochemistry of fluorine, the close match in the ionic radii of fluoride (0.136 nm), hydroxide (0.140 nm), and oxide ion (0.140 nm) allows a sequential replacement of oxygen by fluorine in a wide variety of minerals. This accounts for the wide dissemination of the element in nature. The ready formation of volatile silicon tetrafluoride, the pyrohydrolysis of fluorides to hydrogen fluoride, and the low solubility of calcium fluoride and of calcium fluorophosphates, have provided a geochemical cycle in which fluorine may be stripped from solution by limestone and by apatite to form the deposits of fluorspar and of phosphate rock (fluoroapatite [1306-01 -0]) approximately CaF2 3Ca2(P0 2 which ate the world s main resources of fluorine (1). 

Solubility. High calcium limestone is only very faintly soluble in water. In cold C02-free water it is often regarded as insoluble. Between 17 and... 

The second most common alkalinity control agent is lime [1305-78-8] normally in the form of calcium hydroxide [1303-62-0], used in both water and oH muds. In the latter, the lime reacts with added emulsifiers and fatty acids to stabHi2e water-in-oH emulsions. Lime is used in brine systems containing substantial quantities of soluble calcium and in high pH lime muds. Concentrations are ca 6—57 kg/m (2—20 lb /bbl) (see Lime AND LIMESTONE). 

Deflocculation and Slurry Thinning. Sihcates are used as deflocculants, ie, agents that maintain high sohds slurry viscosities at increased sohds concentrations. Soluble sihcates suppress the formation of ordered stmctures within clay slurries that creates resistance to viscous flow within the various sytems. Laboratory trials are necessary, because the complexity of the systems precludes the use of a universal deflocculant. Sihcates are employed in thinning of limestone or clay slurries used in the wet-process manufacture of cements and bricks, clay refining, and petroleum drilling muds (see also... 

In the dual or double alkaU process, an alkaU salt that is considerably more soluble ia water than limestone is used. The alkaU salt is then regenerated usiag a second alkaU, CaCO. There are several alkaUes used ia the absorber the most common are magnesium sulfite, sodium sulfite, and ammonium sulfite. A typical process usiag magnesium sulfite iSjAbsorption... 

The solubility of calcium carbonate is such that in a saturated solution the product of ion concentrations [Ca+2][C0 2] is 5 X I0 B. Though this may seem quite small, it is large enough to be important to man, especially if he lives in a region of the earth where there are extensive limestone deposits. Calcium carbonate can be dissolved in water, especially if it contains much dissolved C02. This is objectionable because soap added to water which contains even traces of Ca+2 forms a precipitate of calcium stearate. This is the ring that is so difficult to remove from the bathtub. 

The amount of hardness present in natural surface and groundwaters depends to a large extent on the action of dissolved carbon dioxide in rainwater on the watershed s geological formations (such as limestone, dolomite, gypsum, or magnesite). The dissolved hardness levels remain relatively low because of the sparingly soluble nature of the salts formed. Typically, MU water sources initially contain anywhere from 5... 

As the water runs over and through the ground, the carbonic acid reacts with the calcium carbonate of limestone or chalk and forms the more soluble hydrogen carbonate ... 

The potassium carbonate is soluble and washes away, but the aluminosilicate remains as the clay. Cements are obtained when aluminosilicates are roasted with limestone and other minerals and then allowed to solidify (see Section 14.10). 

Over the eons, the flow and evaporation of water inside a cavern creates a stunning array of rock sculptures. Stalagmites grow upward from the floor, sometimes joining stalactites to form massive columns. Limestone dams create beautiful pools of water. Limestone draperies fall like curtains from water flowing around overhanging rock. Delicate mineral flowers sprout from the walls. All these features result from the aqueous solubility equilibrium of calcium carbonate. 

The limestone deposits that decorate Carlsbad and other caverns are the result of the solubility equilibrium of calcium carbonate in groundwater, as described in Chapter 16 ... 

In general, chelating agents possess some unique chemical characteristics. The most significant attribute of these chemicals is the high solubility of the free acids in aqueous solutions. Linear core flood tests were used to study the formation of wormholes. Both hydroxyethylethylene diaminetriacetic acid and hydroxyethyliminodiacetic acid produced wormholes in limestone cores when tested at 150° F. However, the efficiency and capacities differ. Because these chemicals have high solubility in the acidic pH range, it was possible to test acidic (pH less than 3.5) formulations [644]. 

The carbonic acid thus formed is rich in oxygen-16. The mildly acid ground-water as well as the water of rivers and lakes, which is, therefore, also enriched in oxygen-16, dissolves limestone from surrounding rocks, to form calcium bicarbonate, which is soluble in water ... 

The action of carbonic acid on limestone produces a calcium bicarbonate solution that is exceedingly soluble in water. (For comparison, at 20°C the solubility of calcium carbonate in water is only 0.0145 g per liter while the solubility of calcium bicarbonate is 166 g per literJ ) Magnesium ions from dolomite are also released into aqueous solution according to the same mechanism. The weathering of gypsum, calcium sulfate, also releases calcium ions into natural water supplies. 

Tap water in some parts of the country contains large amounts of calcium and magnesium ions. The calcium usually enters the water as it seeps through limestone and chalk, since these rocks are sparingly soluble. 

If global warming raises the temperature of surface waters and carbon dioxide continues to build up in the atmosphere, the carbon dioxide is less soluble in warmer water. The dissolved carbon dioxide can easily move back into the atmosphere unless it is taken up by marine plants or combines with a molecule of carbonate. But, the ocean s supply of carbonate is limited and is replenished only slowly as it is washed into the oceans by rivers that erode carbonate-containing rocks such as limestone. By absorbing two billion tons of carbon from the atmosphere each year, the ocean is depleting its buffer carbonate supply. 

The pigment phase holds potential for manipulation of the paint properties. For example, in antifouling paints, seawater-soluble pigments play an active role in the paint behaviour (see e.g. Kiil et al., 2002 and later sections on mechanisms). Extenders (fillers) are coarse particles (e.g. natural limestone or clay). They are cheap and added for economic reasons, but also provide strength and resistance to the paint. 

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