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Calcium oxide (formula: Ca O), commonly known as quicklime or burnt lime, is a widely used chemical compound.It is a white, caustic, alkaline, crystalline solid at room temperature.
Limewater is a saturated aqueous solution of calcium hydroxide. Calcium hydroxide is sparsely soluble at room temperature in water (1.5 g/L at 25 °C [23]). "Pure" (i.e. less than or fully saturated) limewater is clear and colorless, with a slight earthy smell and an astringent/bitter taste.
Besides the simple oxide CaO, calcium peroxide, CaO 2, can be made by direct oxidation of calcium metal under a high pressure of oxygen, and there is some evidence for a yellow superoxide Ca(O 2) 2. [16] Calcium hydroxide, Ca(OH) 2, is a strong base, though not as strong as the hydroxides of strontium, barium or the alkali metals. [17]
The following chart shows the solubility of various ionic compounds in water at 1 atm pressure and room temperature (approx. 25 °C, 298.15 K). "Soluble" means the ionic compound doesn't precipitate, while "slightly soluble" and "insoluble" mean that a solid will precipitate; "slightly soluble" compounds like calcium sulfate may require heat to precipitate.
A reaction between aqueous solutions of an acid and a base is called neutralization, producing a solution of water and a salt in which the salt separates into its component ions. If the aqueous solution is saturated with a given salt solute, any additional such salt precipitates out of the solution.
An aqueous solution is a solution in which the solvent is water. It is mostly shown in chemical equations by appending (aq) to the relevant chemical formula . For example, a solution of table salt , also known as sodium chloride (NaCl), in water would be represented as Na + (aq) + Cl − (aq) .
When a salt of a metal ion, with the generic formula MX n, is dissolved in water, it will dissociate into a cation and anions. [citation needed]+ + (aq) signifies that the ion is aquated, with cations having a chemical formula [M(H 2 O) p] q+ and anions whose state of aquation is generally unknown.
Calcium peroxide or calcium dioxide is the inorganic compound with the formula CaO 2. It is the peroxide (O 2 2−) salt of Ca 2+. Commercial samples can be yellowish, but the pure compound is white. It is almost insoluble in water. [3]