Calcium oxide CAS

CHEMICAL NAME = calcium oxide CAS NUMBER = 1305-78-8 MOLECULAR FORMULA = CaO MOLAR MASS = 56.0 g/mol COMPOSITION = Ca(71.4%) 0(28.6%)... 

Calcium Oxide. [CAS 1305-78-8], CaO (quicklime), white solid, mp 2,570CC. reacts with H.O 10 form calcium hydroxide with the evolution of much heal reacts with H2O vapor and COi of the atmosphere to form caleium hydroxide and carbonate mixture (slaked lime) formed by heating limestone at high temperature (800=C) and removal of CCL. This process is conducted industrially in a lime kiln. 

Ans. The elements in Group VI require two electrons to complete their octets, but calcium. Group II, must lose two elections to complete its octet. The first three elements in Group VI are oxygen, O sulfur, S and selenium, Se. The compounds are CaO, calcium oxide CaS, calcium sulfide and CaSe, calcium selenide. 

Calcium oxide (ca. 1885) (calx, lime, quicklime, and burnt lime) n. CaO. A white powder with affinity for water, with which it combines to form calcium hydroxide. It has been used to remove traces of water in vinyl plastisols. 

Some carbonates are important industrial chemicals. Calcium carbonate occurs naturally in several forms, including limestone, and is used in the production of quicklime, calcium oxide CaO, slaked (or hydrated) lime, calcium hydroxide Ca(OH)2 and cement. 

Oxidation. Oxidation of the -amyl alcohols produces aldehydes, which after continued oxidation can yield acids. This route to aldehydes has httle merit. However, oxidative esterifications with alkah metal hypohaUtes (eg, calcium chlorite, Ca(OCl)2) (49), bromates (eg, sodium bromate, NaBrO )... 

The chemical formula for limestone is CaCOj and upon burning forms calcium oxide (CaO), which is known as burnt lime. Calcium oxide, when mixed with water, forms calcium hydroxide (Ca(OH)2). Calcium hydroxide is used to treat water as a coagulation aid along with aluminum sulfate. 

Besides its use in pyrots, calcium oxide has been used in a number of expl devices such as Jarolunek s igniter, Elliot s Quicklime Explosive , and the various cartridges of Smith and Moore, Arnould, and Steinau (Ref 1). All of these are presented in greater depth above, together with the current usage of the oxide Refs 1) Daniel (1902), 16, 133,134 738 la) T.W. Richards 0. Honigschmid, JACS 32, 1577 (1910) CA 5,840 (1911) 2) E.C. 

Also quicklime, unslaked lime, and calcium oxide. Hydrated lime is calcium hydroxide (Ca(OH)2). ... 

Early studies using calcium oxide, carbonate, and carboxylates reported low activities for the polymerization of LA, even in bulk at 120-180 °C.827,828 PolyGA and copolymers of GA with CL and L-LA have been prepared using Ca(acac)2, but again high temperatures (150-200 °C) are required.829 Under these conditions transesterification occurs, although to a lesser extent than in analogous Sn(Oct)2-initiated polymerizations. 

Fig. 12.13 SEM micrographs and EDX spectra of the SGA-Ca surface before and after soaking in SBF. The EDX spectra clearly show the evolution of the inorganic chemical composition on the surface from silicon and calcium oxide to a calcium phosphate.

Example Calculate the mass of calcium oxide obtained when 20.0 g of calcium carbonate are thermally decomposed (relative atomic masses Ca = 40, C = 12, O = 16). 

Titration of soil pH is an old method that is not widely used today. Basically, an acid soil suspension is prepared and titrated with a standardized base, often sodium hydroxide, although various basic calcium compounds such as calcium oxide (CaO) and calcium hydroxide [Ca(OH)2] can also be used. Because of the dark color of many soils, they are often titrated using a pH meter as the indicator of the end point. A setup for the titration of soil is shown in Figure 10.1. Titration is slow in that it takes some time after the addition of titrant for some semblance of equilibrium to be reached. Once this happens, a reading can be made or simply another addition of titrant made. 

Calcium hydroxide [Ca (OH) ] is known as slaked or hydrated lime and is formed by exposing calcium oxide to water. Slaked lime is less caustic than quick lime. Therefore, it is used to line football fields. (Unslaked lime, CaO, is very caustic when wet, and if it is used on playing fields, players may receive caustic burns.) Calcium hydroxide has many uses, including as an ingredient for stonemasons mortar, cements, whitewash, and soil conditioner (high pH), as a food additive, and as a human depilatory. 

Problem 45 Calculate the quantity of heat released when 100 grams of calcium oxide react with liquid water to form Ca(OH)2 (s). 

Peterson and Scarrah 165) reported the transesterification of rapeseed oil by methanol in the presence of alkaline earth metal oxides and alkali metal carbonates at 333-336 K. They found that although MgO was not active for the transesterification reaction, CaO showed activity, which was enhanced by the addition of MgO. In contrast, Leclercq et al. 166) showed that the methanolysis of rapeseed oil could be carried out with MgO, although its activity depends strongly on the pretreatment temperature of this oxide. Thus, with MgO pre-treated at 823 K and a methanol to oil molar ratio of 75 at methanol reflux, a conversion of 37% with 97% selectivity to methyl esters was achieved after 1 h in a batch reactor. The authors 166) showed that the order of activity was Ba(OH)2 > MgO > NaCsX zeolite >MgAl mixed oxide. With the most active catalyst (Ba(OH)2), 81% oil conversion, with 97% selectivity to methyl esters after 1 h in a batch reactor was achieved. Gryglewicz 167) also showed that the transesterification of rapeseed oil with methanol could be catalyzed effectively by basic alkaline earth metal compounds such as calcium oxide, calcium methoxide, and barium hydroxide. Barium hydroxide was the most active catalyst, giving conversions of 75% after 30 min in a batch reactor. Calcium methoxide showed an intermediate activity, and CaO was the least active catalyst nevertheless, 95% conversion could be achieved after 2.5 h in a batch reactor. MgO and Ca(OH)2 showed no catalytic activity for rapeseed oil methanolysis. However, the transesterification reaction rate could be enhanced by the use of ultrasound as well as by introduction of an appropriate co-solvent such as THF to increase methanol solubility in the phase containing the rapeseed oil. 

Violent reactions occur in dilute mineral acids with evolution of hydrogen. Ca reacts with carbon dioxide on heating, forming calcium oxide and calcium carbide ... 

Calcium hydroxide on heating at 580°C loses its water, forming calcium oxide (CaO). Ca(OH)2 forms calcium carbonate by absorbing CO2 from air or when CO2 is passed through a suspension in water. Reaction with sulfuric acid yields calcium sulfate dihydrate ... 

It combines with sulfur dioxide to form calcium sulfite hemihydrate, CaSOs MiH20 which can oxidize in air in the presence of moisture to give calcium sulfate dihydrate, CaS04 2H2O. However, when SO2 is passed through a solution of calcium hydroxide, calcium bisulfite, Ca(HS03)2 is obtained. The solution is yellowish when it contains bisulfite in aqueous SO2. 

B) Calcium oxide, also known as Time is a white crystalline solid and is manufactured by heating limestone, coral, sea shells, or chalk, which are mainly CaCOs, to drive off carbon dioxide. This reaction is reversible calcium oxide will react with carbon dioxide to form calcium carbonate. CaO reacts with H to form Ca and H2O. 

D) Adding water to calcium oxide produces calcium hydroxide (CaO + H2O -> Ca(OH)2). 

The hypochlorous acid oxidizes the cell walls and kills bacteria. Solid calcium hypochlorite, Ca(OCl)2, and liquid solutions of sodium hypochlorite, NaOCl, can be used to generate hypochlorous acid in place of chlorine gas, for example, in chlorinating swimming pools. The hypochlorite ion generated from Ca(OCl)2 and NaOCl forms an equilibrium with water represented by the equation ... 

A shorthand notation is often nsed to designate the oxides (e.g., C for CaO and A for AI2O3 see Table 5.7), and it is also used to designate the compounds formed between the components during heating, such as calcium aluminate (CA) and tricalcium silicate (C3S) ... 

Calcium oxide crystallizes with a face-centred cubic lattice, a=481 pm and a density /)=3.35x10 kg m calculate a value for Z (Atomic masses of Ca and 0 are 40.08 and 15.999, respectively.)... 

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