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1 décembre 2011 4 01 /12 /décembre /2011 02:05

Research into cancer prevention

The role that calcium might have in reducing the rates of colorectal cancer has been the subject of many studies. However, given its modest efficacy, there is no current medical recommendation to use calcium for cancer reduction. Several epidemiological studies suggest that people with high calcium intake have a reduced risk of colorectal cancer.Sony VAIO VGN-Z46MD/B Battery

These observations have been confirmed by experimental studies in volunteers and in rodents. One large scale clinical trial shows that 1.2 g calcium each day reduces, modestly, intestinal polyps recurrence in volunteers. Data from the four published trials are available.Sony VAIO VGN-Z46SD/B Battery

Some forty carcinogenesis studies in rats or mice, reported in the Chemoprev.Database, also support that calcium could prevent intestinal cancer.

Calcium carbonate is a chemical compound with the formula CaCO3. It is a common substance found in rocks in all parts of the world, and is the main component of shells of marine organisms, snails, coal balls, pearls, and eggshells. Sony VAIO VGN-Z46TD/B Battery

Calcium carbonate is the active ingredient in agricultural lime, and is usually the principal cause of hard water. It is commonly used medicinally as a calcium supplement or as an antacid, but excessive consumption can be hazardous.

The vast majority of calcium carbonate used in industry is extracted by mining or quarrying. Pure calcium carbonate (e.g. for food or pharmaceutical use), can be produced from a pure quarried source (usually marble).Sony VAIO VGN-Z46TD/R Battery

Alternatively, calcium carbonate is prepared by calcining crude calcium oxide. Water is added to give calcium hydroxide, andcarbon dioxide is passed through this solution to precipitate the desired calcium carbonate, referred to in the industry as precipitated calcium carbonate (PCC):Sony VAIO VGN-Z47GD/X Battery

Carbonate is found frequently in geologic settings and constitute an enormous carbon reservoir. Calcium carbonate occurs as thepolymorphs aragonite and calcite. A polymorph is a mineral with the same chemical formula but different chemical structure. The carbonate minerals form the rock types: limestone, chalk, marble, travertine, tufa, and others. Sony VAIO VGN-Z48GD/X Battery

Calcite commonly occurs as sediments in marine settings. Calcite is typically found around the warm tropic environments. Calcite precipitates in warmer shallow environments more than it does under colder environments because warmer environments do not favor the dissolution of CO2Sony VAIO VGN-Z48TD/X Battery

This is analogous to CO2 being dissolved in soda. When you take the cap off of a soda bottle, the CO2 rushes out. As the soda warms up, carbon dioxide is released. This same principle can be applied to calcite in the ocean. Cold-water carbonates do exist at higher latitudes but have a very slow growth rate.Sony VAIO VGN-Z51WG/B Battery

In tropic settings, the waters are warm and clear. Corals are more abundant in this environment than towards the poles where the waters are cold. Calcium carbonate contributors, including plankton (such as coccoliths and planktic foraminifera), coralline algae, sponges, brachiopods, echinoderms, bryozoa and mollusks, Sony VAIO VGN-Z51XG/B Battery

are typically found in shallow water environments where sunlight and filterable food are more abundant. The calcification processes are changed by the ocean acidification.

Where the oceanic crust is subducted under a continental plate sediments will be carried down to warmer zones in the astenosphere and mesosphere where the calcium carbonate is decomposed to carbon dioxide which will give rise to explosive vulcanic eruptions.Sony VAIO VGN-Z530N/B Battery

Carbonate compensation depth

The carbonate compensation depth (CCD) is the point in the ocean where the rate of precipitation of calcium carbonate is balanced by the rate of dissolution due to the conditions present. Deep in the ocean, the temperature drops and pressure increases. Calcium carbonate is unusual in that its solubility increases with decreasing temperature. Sony VAIO VGN-Z540EBB Battery

Increasing pressure also increases the solubility of calcium carbonate. The CCD can range from 4–6 km below sea level.

Taphonomy

Calcium carbonate can preserve fossils through permineralization. Most of the vertebrate fossils of the Two Medicine Formation, known for its duck-billed dinosaur eggs, are preserved by CaCO3 permineralization.Sony VAIO VGN-Z540NLB Battery

This type of preservation preserves high levels of detail, even down to the microscopic level. However, it also leaves specimens vulnerable to weathering when exposed to the surface.

Industrial applications

The main use of calcium carbonate is in the construction industry,Sony VAIO VGN-Z540NMB Battery

either as a building material or limestone aggregate for roadbuilding or as an ingredient of cement or as the starting material for the preparation of builder's lime by burning in a kiln. However, due to weathering mainly caused by acid rain, calcium carbonate (in limestone form) is no longer used for building purposes on its own, and only as a raw/primary substance for building materials.Sony VAIO VGN-Z550N/B Battery

Calcium carbonate is also used in the purification of iron from iron ore in a blast furnace. The carbonate is calcined in situ to give calcium oxide, which forms a slag with various impurities present, and separates from the purified iron.

In the oil industry, calcium carbonate is added to drilling fluids as a formation-bridging and filtercake-sealing agent;Sony VAIO VGN-Z55F Battery

it is also a weighting material which increases the density of drilling fluids to control the downhole pressure. Calcium carbonate is added to swimming pools, as a pH corrector for maintaining alkalinityand offsetting the acidic properties of the disinfectant agent.Sony VAIO VGN-Z55TG/B Battery

Calcium carbonate has traditionally been a major component of blackboard chalk. However, modern manufactured chalk is mostly gypsum, hydrated calcium sulfateCaSO4·2H2O. Calcium carbonate is a main source for growing Seacrete, or Biorock.Sony VAIO VGN-Z56GG/B Battery

Precipitated calcium carbonate (PCC), pre-dispersed in slurry form, is a common filler material for latex gloves with the aim of achieving maximum saving in material and production costs. Sony VAIO VGN-Z56GG/E Battery

Fine ground calcium carbonate (GCC) is an essential ingredient in the microporous film used in babies' diapers and some building films as the pores are nucleated around the calcium carbonate particles during the manufacture of the film by biaxial stretching. GCC or PCC is used as a filler in paper because they are cheaper than wood fiber.Sony VAIO VGN-Z56GGX Battery

Printing and writing paper can contain 10–20% calcium carbonate. In North America, calcium carbonate has begun to replace kaolin in the production of glossy paper. Europe has been practicing this as alkaline papermaking or acid-free papermaking for some decades. Sony VAIO VGN-Z56TG/B Battery

PCC has a very fine and controlled particle size, on the order of 2 micrometres in diameter, useful in coatings for paper.

Calcium carbonate is widely used as an extender in paints,  in particular matte emulsion paint where typically 30% by weight of the paint is either chalk or marble. It is also a popular filler in plastics.Sony VAIO VGN-Z56TG/E Battery

Some typical examples include around 15 to 20% loading of chalk in unplasticized polyvinyl chloride (uPVC) drain pipe, 5 to 15% loading of stearate coated chalk or marble in uPVC window profile. PVC cables can use calcium carbonate at loadings of up to 70 phr (parts per hundred parts of resin) to improve mechanical properties (tensile strength and elongation)Sony VAIO VGN-Z56TG/R Battery

and electrical properties (volume resistivity). Polypropylene compounds are often filled with calcium carbonate to increase rigidity, a requirement that becomes important at high use temperatures. It also routinely used as a filler inthermosetting resins (sheet and bulk molding compounds) and has also been mixed with ABS,Sony VAIO VGN-Z570N/B Battery

and other ingredients, to form some types of compression molded "clay" poker chips. Precipitated calcium carbonate, made by dropping calcium oxide into water, is used by itself or with additives as a white paint, known as whitewashing.

Calcium carbonate is added to a wide range of trade and do it yourself adhesives, sealants, and decorating fillers.Sony VAIO VGN-Z57G Battery

Ceramic tile adhesives typically contain 70 to 80% limestone. Decorating crack fillers contain similar levels of marble or dolomite. It is also mixed with putty in setting stained glass windows, and as a resist to prevent glass from sticking to kiln shelves when firing glazes and paints at high temperature.Sony VAIO VGN-Z57GG/X Battery

In ceramics/glazing applications, calcium carbonate is known as whiting, and is a common ingredient for many glazes in its white powdered form. When a glaze containing this material is fired in a kiln, the whiting acts as a flux material in the glaze. Ground calcium carbonate is an abrasive (both as scouring powder and as an ingredient of household scouring creams), Sony VAIO VGN-Z57GGX Battery

in particular in its calcite form, which has the relatively low hardness level of 3 on the Mohs scale of mineral hardness, and will therefore not scratch glass and most other ceramics, enamel, bronze, iron, and steel, and have a moderate effect on softer metals like aluminiumand copper. Sony VAIO VGN-Z57TG/X Battery

A paste made from calcium carbonate and deionized water can be used to clean tarnish on silver .

Health and dietary applications

Calcium carbonate is widely used medicinally as an inexpensive dietary calcium supplement or gastric antacid.Sony VAIO VGN-Z58GG/X Battery

It may be used as a phosphate binder for the treatment of hyperphosphatemia (primarily in patients with chronic renal failure). It is also used in the pharmaceutical industry as an inert filler for tablets and other pharmaceuticals.

Calcium carbonate is known among IBS sufferers to help reduce diarrhea. Some individuals report being symptom-free since starting supplementation. Sony VAIO VGN-Z58GGX Battery

The process in which calcium carbonate reduces diarrhea is by binding water in the bowel, which creates a stool that is firmer and better formed. Calcium carbonate supplements are often combined with magnesium in various proportions. This should be taken into account as magnesium is known to cause diarrhea.Sony VAIO VGN-Z590NJB Battery

Calcium carbonate is used in the production of toothpaste and has seen a resurgence as a food preservative and color retainer, when used in or with products such as organic apples or food.

Excess calcium from supplements, fortified food and high-calcium diets, can cause the milk-alkali syndrome, which has serious toxicity and can be fatal. Sony VAIO VGN-Z590UAB Battery

In 1915, Bertram Sippy introduced the "Sippy regimen" of hourly ingestion of milk and cream, and the gradual addition of eggs and cooked cereal, for 10 days, combined with alkaline powders, which provided symptomatic relief for peptic ulcer disease. Over the next several decades, the Sippy regimen resulted in renal failure, alkalosis, and hypercalcemia, mostly in men with peptic ulcer disease.Sony VAIO VGN-Z591U/B Battery

These adverse effects were reversed when the regimen stopped, but it was fatal in some patients with protracted vomiting. Milk alkali syndrome declined in men after effective treatments for peptic ulcer disease arose. During the past 15 years, it has been reported in women taking calcium supplements above the recommended range of 1.2 to 1.5 g daily, Sony VAIO VGN-Z59G Battery

for prevention and treatment of osteoporosis, and is exacerbated by dehydration. Calcium has been added to over-the-counter products, which contributes to inadvertent excessive intake. Excessive calcium intake can lead to hypercalcemia, complications of which include vomiting, abdominal pain and altered mental status.Sony VAIO VGN-Z620D Battery

As a food additive it is designated E170 ; INS number 170. Used as an acidity regulator, anticaking agent, stabiliser or colour it is approved for usage in the EU, USA and Australia and New Zealand. It is used in some soy milk products as a source of dietary calcium; one study suggests that calcium carbonate might be as bioavailable as the calcium in cow's milk.Sony VAIO VGN-Z620N/B Battery

Calcium carbonate is also used as a firming agent in many canned or bottled vegetable products.

Environmental applications

In 1989, a researcher, Ken Simmons, introduced CaCO3 into the Whetstone Brook in Massachusetts. His hope was that the calcium carbonate would counter the acid in the stream from acid rain and save the trout that had ceased to spawn. Sony VAIO VGN-Z650N/B Battery

Although his experiment was a success, it did increase the amounts of aluminium ions in the area of the brook that was not treated with the limestone. This shows that CaCO3 can be added to neutralize the effects of acid rain in river ecosystems. Currently calcium carbonate is used to neutralize acidic conditions in both soil and water.Sony VAIO VGN-Z670N/B Battery

Since the 1970s, such liming has been practiced on a large scale in Sweden to mitigate acidification and several thousand lakes and streams are limed repeatedly.

Calcination equilibrium

Calcination of limestone using charcoal fires to produce quicklime has been practiced since antiquity by cultures all over the world.Sony VAIO VGN-Z690CTO Battery

The temperature at which limestone yields calcium oxide is usually given as 825 °C, but stating an absolute threshold is misleading. Calcium carbonate exists in equilibrium with calcium oxide and carbon dioxide at any temperature. At each temperature there is a partial pressure of carbon dioxide that is in equilibrium with calcium carbonate. Sony VAIO VGN-Z690NAX Battery

At room temperature the equilibrium overwhelmingly favors calcium carbonate, because the equilibrium CO2 pressure is only a tiny fraction of the partial CO2 pressure in air, which is about 0.035 kPa.

At temperatures above 550 °C the equilibrium CO2 pressure begins to exceed the CO2 pressure in air.Sony VAIO VGN-Z690PAB Battery

So above 550 °C, calcium carbonate begins to outgas CO2 into air. However, in a charcoal fired kiln, the concentration of CO2 will be much higher than it is in air. Indeed if all the oxygen in the kiln is consumed in the fire, then the partial pressure of CO2 in the kiln can be as high as 20 kPa.Sony VAIO VGN-Z690PCB Battery

The table shows that this equilibrium pressure is not achieved until the temperature is nearly 800 °C. For the outgassing of CO2 from calcium carbonate to happen at an economically useful rate, the equilibrium pressure must significantly exceed the ambient pressure of CO2.Sony VAIO VGN-Z690PDB Battery

And for it to happen rapidly, the equilibrium pressure must exceed total atmospheric pressure of 101 kPa, which happens at 898 °C.

Calcium carbonate is poorly soluble in pure water (47 mg/L at normal atmospheric CO2 partial pressure as shown below).

The equilibrium of its solution is given by the equation (with dissolved calcium carbonate on the right):Sony VAIO VGN-Z690PEB Battery

CaCO3  Ca2+ + CO32–       Ksp = 3.7×10?9 to 8.7×10?9 at 25 °C

where the solubility product for [Ca2+][CO32–] is given as anywhere from Ksp = 3.7×10?9 to Ksp = 8.7×10?9 at 25 °C, depending upon the data source.Sony VAIO VGN-Z690PFB Battery

What the equation means is that the product of molar concentration of calcium ions (moles of dissolved Ca2+ per liter of solution) with the molar concentration of dissolved CO32– cannot exceed the value of Ksp. This seemingly simple solubility equation, however, must be taken along with the more complicated equilibrium of carbon dioxide with water (see carbonic acid). Sony VAIO VGN-Z690YAD Battery

Some of the CO32– combines with H+ in the solution according to:

HCO3–  H+ + CO32–         Ka2 = 5.61×10?11 at 25 °C

HCO3– is known as the bicarbonate ion. Calcium bicarbonate is many times more soluble in water than calcium carbonate—indeed it exists only in solution.Sony VAIO VGN-Z691Y/B Battery

Some of the HCO3– combines with H+ in solution according to:

H2CO3  H+ + HCO3–        Ka1 = 2.5×10?4 at 25 °C

Some of the H2CO3 breaks up into water and dissolved carbon dioxide according to:Sony VAIO VGN-Z691Y/X Battery

H2O + CO2(dissolved)  H2CO3        Kh = 1.70×10?3 at 25 °C

And dissolved carbon dioxide is in equilibrium with atmospheric carbon dioxide according to:

where kH = 29.76 atm/(mol/L) at 25 °C (Henry constant),  being the CO2 partial pressure.Sony VAIO VGN-Z698Y/X Battery

For ambient air,  is around 3.5×10?4 atmospheres (or equivalently 35 Pa). The last equation above fixes the concentration of dissolved CO2 as a function of , independent of the concentration of dissolved CaCO3. At atmospheric partial pressure of CO2, dissolved CO2 concentration is 1.2×10?5 moles/liter.Sony VAIO VGN-Z699JAB Battery

The equation before that fixes the concentration of H2CO3 as a function of [CO2]. For [CO2]=1.2×10?5, it results in [H2CO3]=2.0×10?8 moles per liter. When [H2CO3] is known, the remaining three equations together with

H2O  H+ + OH–    K = 10?14 at 25 °C

(which is true for all aqueous solutions), and the fact that the solution must be electrically neutral,Sony VAIO VGN-Z70B Battery

2[Ca2+] + [H+] = [HCO3–] + 2[CO32–] + [OH–]

make it possible to solve simultaneously for the remaining five unknown concentrations (note that the above form of the neutrality equation is valid only if calcium carbonate has been put in contact with pure water or with a neutral pH solution; in the case where the origin water solvent pH is not neutral, the equation is modified).Sony VAIO VGN-Z71JB Battery

The table on the right shows the result for [Ca2+] and [H+] (in the form of pH) as a function of ambient partial pressure of CO2(Ksp = 4.47×10?9 has been taken for the calculation).

  • At atmospheric levels of ambient CO2 the table indicates the solution will be slightly alkaline with a maximum CaCO3 solubility of 47 mg/L.Sony VAIO VGN-Z73FB Battery
  • As ambient CO2 partial pressure is reduced below atmospheric levels, the solution becomes more and more alkaline. At extremely low  , dissolved CO2, bicarbonate ion, and carbonate ion largely evaporate from the solution, leaving a highly alkaline solution of calcium hydroxide, which is more soluble than CaCO3Sony VAIO VGN-Z790DKX Battery
  • Note that for   = 10?12 atm, the [Ca2+][OH?]2 product is still below the solubility product of Ca(OH)2 (8×10?6). For still lower CO2 pressure, Ca(OH)2 precipitation will occur before CaCO3 precipitation.
  • As ambient CO2 partial pressure increases to levels above atmospheric, pH drops, and much of the carbonate ion is converted to bicarbonate ion, which results in higher solubility of Ca2+.Sony VAIO VGN-Z790DMR Battery

The effect of the latter is especially evident in day-to-day life of people who have hard water. Water in aquifers underground can be exposed to levels of CO2 much higher than atmospheric. As such water percolates through calcium carbonate rock, the CaCO3dissolves according to the second trend.Sony VAIO VGN-Z790DND Battery

When that same water then emerges from the tap, in time it comes into equilibrium with CO2 levels in the air by outgassing its excess CO2. The calcium carbonate becomes less soluble as a result and the excess precipitates as lime scale. This same process is responsible for the formation of stalactites and stalagmites in limestone caves.Sony VAIO VGN-Z820DB Battery

Two hydrated phases of calcium carbonate, monohydrocalcite, CaCO3·H2O and ikaite, CaCO3·6H2O, may precipitate from water at ambient conditions and persist as metastable phases.

With varying pH

Consider the problem of the maximum solubility of calcium carbonate in normal atmospheric conditions (  = 3.5 × 10?4 atm) when the pH of the solution is adjusted. Sony VAIO VGN-Z820G/B Battery

This is for example the case in a swimming pool where the pH is maintained between 7 and 8 (by addition of sodium bisulfate NaHSO4to decrease the pH or ofsodium bicarbonate NaHCO3 to increase it). From the above equations for the solubility product, the hydration reaction and the two acid reactions, the following expression for the maximum [Ca2+] can be easily deduced:Sony VAIO VGN-Z890GLX Battery

  • decreasing the pH from 8 to 7 increases the maximum Ca2+ concentration by a factor 100. Water with a pH maintained to 7 can dissolve up to 15.9 mg/L of CaCO3. This explains the high Ca2+ concentration in some mineral waters with pH close to 7.
  • note that the Ca2+ concentration of the previous table is recovered for pH = 8.27Sony VAIO VGN-Z890GMR Battery
  • keeping the pH to 7.4 in a swimming pool (which gives optimum HClO/ClO? ratio in the case of "chlorine" maintenance) results in a maximum Ca2+ concentration of 1010 mg/L. This means that successive cycles of water evaporation and partial renewing may result in a very hard water before CaCO3 precipitates (water with a Ca2+concentration above 120 mg/L is considered very hard). Addition of a calcium sequestering agent or complete renewing of the water will solve the problem.Sony VAIO VGN-Z898H/X Battery

Solubility in a strong or weak acid solution

Solutions of strong (HCl), moderately strong (sulfamic) or weak (acetic, citric, sorbic, lactic, phosphoric) acids are commercially available. They are commonly used as descaling agents to remove limescale deposits. The maximum amount of CaCO3 that can be "dissolved" by one liter of an acid solution can be calculated using the above equilibrium equations.Sony VAIO VGN-Z90FS Battery

  • In the case of a strong monoacid with decreasing acid concentration [A] = [A?], we obtain (with CaCO3 molar mass = 100 g):

where the initial state is the acid solution with no Ca2+ (not taking into account possible CO2 dissolution) and the final state is the solution with saturated Ca2+Sony VAIO VGN-Z90NS Battery

For strong acid concentrations, all species have a negligible concentration in the final state with respect to Ca2+ and A? so that the neutrality equation reduces approximately to 2[Ca2+] = [A?] yielding  . When the concentration decreases, [HCO3?] becomes non-negligible so that the preceding expression is no longer valid. Sony VAIO VGN-Z90PS Battery

For vanishing acid concentrations, one can recover the final pH and the solubility of CaCO3 in pure water.

  • In the case of a weak monoacid (here we take acetic acid with pKA = 4.76) with decreasing total acid concentration [A] = [A?]+[AH], we obtain:Sony VAIO VGN-Z90S Battery

For the same total acid concentration, the initial pH of the weak acid is less acid than the one of the strong acid; however, the maximum amount of CaCO3 which can be dissolved is approximately the same. This is because in the final state, the pH is larger than the pKA, so that the weak acid is almost completely dissociated, yielding in the end as many H+ ions as the strong acid to "dissolve" the calcium carbonate.Sony VAIO VGN-Z90US Battery

  • The calculation in the case of phosphoric acid (which is the most widely used for domestic applications) is more complicated since the concentrations of the four dissociation states corresponding to this acid must be calculated together with [HCO3?], [CO32?], [Ca2+], [H+] and [OH?]. Sony VAIO VGN-Z91DS Battery
  • The system may be reduced to a seventh degree equation for [H+] the numerical solution of which gives

where [A] = [H3PO4] + [H2PO4?] + [HPO42?] + [PO43?] is the total acid concentration. Thus phosphoric acid is more efficient than a monoacid since at the final almost neutral pH, the second dissociated state concentration [HPO42?] is not negligible (see phosphoric acid).Sony VAIO VGN-Z91JS Battery

Calcium chloride, CaCl2, is a salt of calcium and chlorine. It behaves as a typical ionic halide, and is solid at room temperature. Common applications include brine for refrigeration plants, ice and dust control on roads, and desiccation. Because of its hygroscopic nature, anhydrous calcium chloride must be kept in tightly-sealed air-tight containers.Sony VAIO VGN-Z91PS Battery

Calcium chloride can serve as a source of calcium ions in a solution as calcium chloride is soluble. This property can be useful for displacing ions from solution. For example, phosphate is displaced from solution by calcium:

3 CaCl2 (aq) + 2 K3PO4 (aq) ? Ca3(PO4)2 (s) + 6 KCl (aq)

Molten calcium chloride can be electrolysed to give calcium metal and chlorine gas:Sony VAIO VGN-Z91YS Battery

CaCl2 (l) ? Ca (s) + Cl2 (g)

Calcium chloride has a very high enthalpy change of solution.

The anhydrous salt is deliquescent; it can accumulate enough water in its crystal lattice to form a solution.Sony VAIO VGN-Z92DS Battery

Preparation

Calcium chloride can be produced directly from limestone, but large amounts are also produced as a by-product of the Solvay process. North American consumption in 2002 was 1,687,000 tons (3.7 billion pounds). A Dow Chemical Company manufacturing facility in Michigan, houses about 35% of the total U.S. production capacity for calcium chloride.Sony VAIO VGN-Z92JS Battery

Occurrence

Calcium chloride occurs as the rare evaporite minerals sinjarite (dihydrate) and antarcticite (hexahydrate). A related mineral chlorocalcite (potassium calcium chloride, KCaCl3) is also very rare.Sony VAIO VGN-Z92PS Battery

Desiccant

Drying tubes are frequently packed with calcium chloride. Kelp is dried with calcium chloride for use producing sodium carbonate. Adding solid calcium chloride to liquids can remove dissolved water. Calcium chloride is also used in products such as DampRid and Dri-Z-Air which is advertised as an air moisture absorber.Sony VAIO VGN-Z92YS Battery

Anhydrous calcium chloride has been approved by the FDA as a packaging aid to ensure dryness (CPG 7117.02).

These hygroscopic properties are also applied to keep a liquid layer on the surface of the roadway, which holds dust down.Sony VAIO VGN-Z93FS Battery

Deicing and freezing point depression

By depressing the freezing-point calcium chloride is used to prevent ice formation and to deice. This is particularly useful on road surfaces. Calcium chloride dissolution is exothermic, and is relatively harmless to plants and soil; however, recent observations in Washington state suggest it may be particularly harsh on roadside evergreen trees.Sony VAIO VGN-Z93GS Battery

It is also more effective at lower temperatures than sodium chloride. When distributed for this use, it usually takes the form of small white balls a few millimeters in diameter, called prills. Solutions of calcium chloride can prevent freezing at temperature as low as ?52 °C (?62 °F), making it ideal for filling agricultural implement tires as a liquid ballast, aiding traction in cold climates.Sony VAIO VGN-Z93HS Battery

Source of calcium ions

Calcium chloride is used to increase the hardness in swimming pools. This reduces the erosion of the concrete in the pool. ByLe Chatelier's principle and the common ion effect, increasing the concentration of calcium in the water will reduce the dissolution of calcium compounds essential to the structure of concrete.Sony VAIO VGN-Z93VS Battery

In marine aquariums calcium chloride is added to introduce bioavailable calcium for calcium carbonate shelled animals such asmollusks and cnidarians. Calcium hydroxide (kalkwasser mix) or a calcium reactor can also be used to introduce calcium, however calcium chloride addition is the fastest method and has minimal impact on pH.Sony A1258274A Battery

Food

As an ingredient, it is listed as a permitted food additive in the European Union for use as a sequestrant and firming agentwith the E number E509, and considered as generally recognized as safe (GRAS) by the U.S. Food and Drug Administration. The average intake of calcium chloride as food additives has been estimated to be 160–345 mg/day for individuals.Sony VGP-BPL10 Battery

As a firming agent calcium chloride is used in canned vegetables, in firming soy bean curds into tofu and in producing acaviar substitute from vegetable or fruit juices .It is commonly used as an electrolyte in sports drinks and other beverages including Smartwater and Nestle bottled water.Sony VGP-BPS10 Battery

The extremely salty taste of calcium chloride is used to flavorpickles while not increasing the food's sodium content. Calcium chloride's freezing-point depression properties are used, for example, in Cadbury Caramilk chocolate bars to slow the freezing of the caramel.Sony VGP-BPS10/S Battery

In brewing beer, calcium chloride is sometimes used to correct mineral deficiencies in the brewing water. It affects flavor and chemical reactions during the brewing process, and can also affect yeast function during fermentation. Calcium chloride is sometimes added to processed milk to restore the natural balance between calcium and protein in casein for the purposes of making cheese such as brie, Pélardon and stilton.Sony VGP-BPS10A/B Battery

Medicine

Calcium chloride can be injected as intravenous therapy for the treatment of hypocalcaemia. It can be used for magnesium intoxication. Calcium chloride injection may antagonize cardiac toxicity as measured by electrocardiogram. It can help to protect the myocardium from dangerously high levels of serum potassium in hyperkalemia.Sony VGP-BPS10B Battery

Calcium chloride can be used to quickly treat Calcium Channel Blocker toxicity, from the side effects of drugs such as Cardizem — helping avoid potential heart attacks. [11]

Aqueous calcium chloride is used in genetic transformation of cells by increasing the cell membrane permeability, inducingcompetence for DNA uptake (allowing DNA fragments to enter the cell more readily).Sony VGP-BPS10A Battery

Other

Calcium chloride is used in concrete mixes to help speed up the initial setting, but chloride ion leads to corrosion of steelrebar, so it should not be used in reinforced concrete.[12] The anhydrous form of calcium chloride may also be used for this purpose and can provide a measure of the moisture in concrete.Sony VGP-BPS11 Battery

Calcium chloride is used in swimming pool water as a pH buffer and to adjust the calcium hardness of the water.

Calcium chloride is included as an additive in plastics and in fire extinguishers, in wastewater treatment as a drainage aid, in blast furnaces as an additive to control scaffolding (clumping and adhesion of materials that prevent the furnace charge from descending), and in fabric softener as a thinner.Sony VGP-BPL11 Battery

The exothermic dissolution of calcium chloride is used in self-heating cans and heating pads.

In the oil industry calcium chloride is used to increase the density of solids free brines. It is also used to provide inhibition of swelling clays in the water phase of invert emulsion drilling fluids.Sony VGP-BPL12 Battery

Toxicology

Calcium chloride can act as an irritant by desiccating moist skin. Solid calcium chloride dissolves exothermically and burnscan result in the mouth and esophagus if calcium chloride is ingested. Ingestion of concentrated solutions or solid calcium chloride products may cause gastrointestinal irritation or ulceration.Sony VGP-BPS12 Battery,Sony VGP-BPL13 Battery,Sony VGP-BPS13 Battery,Sony VGP-BPS13/B Battery,Sony VGP-BPS13/S Battery

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