Does calcium have a reaction to water?
386748#9
One significant application of calcium hydroxide is as a flocculant, in water and sewage treatment. It forms a fluffy charged solid that aids in the removal of smaller particles from water, resulting in a clearer product. This application is enabled by the low cost and low toxicity of calcium hydroxide. It is also used in fresh water treatment for raising the pH of the water so that pipes will not corrode where the base water is acidic, because it is self-regulating and does not raise the pH too much.
Calcium hydroxide
44731#0
Calcium carbonate is a chemical compound with the formula CaCO. It is a common substance found in rocks as the minerals calcite and aragonite (most notably as limestone, which is a type of sedimentary rock consisting mainly of calcite) and is the main component of pearls and the shells of marine organisms, snails, and eggs. Calcium carbonate is the active ingredient in agricultural lime and is created when calcium ions in hard water react with carbonate ions to create limescale. It is medicinally used as a calcium supplement or as an antacid, but excessive consumption can be hazardous.
Calcium carbonate
51937029#4
While, the solubility of most inorganic salts (NaCl, KCl, ...) increases with temperature (endothermic dissolution reaction) , some inorganic salts such as calcium carbonate and calcium sulfate have also a retrograde solubility, i.e., their solubility decreases with temperature. In the case of calcium carbonate, it is due to the degassing of CO whose solubility decreases with temperature as it is the case for most of the gases (exothermic dissolution reaction in water). In the case of calcium sulfate, the reason is that the dissolution reaction of calcium sulfate itself is exothermic and therefore is favored when the temperature decreases (then, the dissolution heat is more easily evacuated, see Le Chatelier's principle). In other terms, the solubility of calcium carbonate and calcium sulfate increases at low temperature and decreases at high temperature, as it is also the case for calcium hydroxide (portlandite) often referred as a didactic case study to explain the reason of retrograde solubility.
Oilfield scale inhibition
595183#17
The dissolution of the different crystalline phases of calcium sulfate in water is exothermic and release heat (decrease in Enthalpy: ΔH < 0). As an immediate consequence, to proceed, the dissolution reaction needs to evacuate this heat that can be considered as a product of reaction. If the system is cooled, the dissolution equilibrium will evolve towards the right according to the Le Chatelier principle and calcium sulfate will dissolve more easily. The solubility of calcium sulfate increases thus when the temperature decreases. If the temperature of the system is raised, the reaction heat cannot dissipate and the equilibrium will regress towards the left according to Le Chatelier principle. The solubility of calcium sulfate decreases thus when temperature increases. This contra-intuitive solubility behaviour is called retrograde solubility. It is less common than for most of the salts whose dissolution reaction is endothermic (i.e., the reaction consumes heat: increase in Enthalpy: ΔH > 0) and whose solubility increases with temperature. Another calcium compound, calcium hydroxide (Ca(OH), portlandite) also exhibits a retrograde solubility for the same thermodynamic reason: because its dissolution reaction is also exothermic and releases heat. So, to dissolve higher amounts of calcium sulfate or calcium hydroxide in water, it is necessary to cool down the solution close to its freezing point instead of increasing its temperature.
Calcium sulfate
8611364#2
Inside the reaction chamber, a calcium rich media (aragonite), mainly CaCO, is forced into contact with water injected with carbon dioxide (CO) in order to create carbonic acid (HCO). This increases the solubility of the calcium carbonate. The reaction frees the calcium and carbonate, supplying the aquarium with water rich in Ca and CO, important for maintaining alkalinity and calcium levels.
Calcium reactor
6670#5
Non-hydraulic cement, such as slaked lime (calcium oxide mixed with water), hardens by carbonation in the presence of carbon dioxide, which is naturally present in the air. First calcium oxide (lime) is produced from calcium carbonate (limestone or chalk) by calcination at temperatures above 825 °C (1,517 °F) for about 10 hours at atmospheric pressure:
The calcium oxide is then "spent" (slaked) mixing it with water to make slaked lime (calcium hydroxide):
Once the excess water is completely evaporated (this process is technically called "setting"), the carbonation starts:
This reaction takes time, because the partial pressure of carbon dioxide in the air is low. The carbonation reaction requires that the dry cement be exposed to air, so the slaked lime is a non-hydraulic cement and cannot be used under water. This process is called the "lime cycle".
Cement
242643#8
The reaction of calcium carbide with water, producing acetylene and calcium hydroxide, was discovered by Friedrich Wöhler in 1862.
Calcium carbide
1224314#2
The type found deposited on the heating elements of water heaters has a main component of calcium carbonate. Hard water contains calcium (and often magnesium) bicarbonate or similar ions. Calcium salts, such as calcium bicarbonate and calcium carbonate are both more soluble in hot water than cold water. Thus, heating water does not cause calcium carbonate to precipitate per se. However, there is an equilibrium between dissolved calcium bicarbonate and dissolved calcium carbonate:
Limescale
58446217#10
Calcium is an essential component of soil. When deposited in the form of lime, it can't be used by plants. To combat this, carbon dioxide produced by plants reacts with water in the environment to produce carbonic acid. Carbonic acid is then able to dissolve limestone, enabling the release of calcium ions. This reaction is more readily available with smaller particles of limestone than it is with large pieces of rock due to the increased surface area. When lime is leached into soil, calcium levels inevitably increase, both stabilising pH and enabling calcium to mix with water to form a Ca 2+ ions, thus making it soluble and accessible to plants to be absorbed and utilised by the root system. The calcium ions travel up the xylem of the plant alongside water to reach the leaves. The plant can utilise this calcium in the form of calcium pectate to stabilise cell walls and provide rigidity. Calcium is also used by plant enzymes to signal growth and coordinate life-promoting processes . Additionally, the release of calcium ions enables microorganisms to access phosphorus and other micro nutrients with greater ease, improving the soil ecosystem drastically thus indirectly promoting plant growth and nutrition.
Calcium cycle
5906#28
Acids liberate from most metal carbonates. Consequently, it may be obtained directly from natural carbon dioxide springs, where it is produced by the action of acidified water on limestone or dolomite. The reaction between hydrochloric acid and calcium carbonate (limestone or chalk) is shown below:
The carbonic acid () then decomposes to water and :
Such reactions are accompanied by foaming or bubbling, or both, as the gas is released. They have widespread uses in industry because they can be used to neutralize waste acid streams.
Carbon dioxide
23158389#14
In this last reaction, calcium carbonate reacts with sulfuric acid and produce calcium sulfate, water and carbon dioxide.
Byne's disease