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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 . The broadly used term lime connotes calcium-containing inorganic compounds , in which carbonates , oxides , and hydroxides of calcium, silicon , magnesium ...
Commercial heat sources for self-heating food packaging use an exothermic (heat releasing) reaction, for which there are several common formulations. These include: Quicklime aka calcium oxide, and water. Quicklime, inexpensive and readily available, is generally recognized by the FDA as safe. [2] The product of the reaction is calcium hydroxide.
Calcium hydroxide (traditionally called slaked lime) is an inorganic compound with the chemical formula Ca 2. It is a colorless crystal or white powder and is produced when quicklime (calcium oxide) is mixed with water. Annually, approximately 125 million tons of calcium hydroxide are produced worldwide. [8]
The root of the word calcination refers to its most prominent use, which is to remove carbon from limestone (calcium carbonate) through combustion to yield calcium oxide (quicklime). This calcination reaction is CaCO 3 (s) → CaO(s) + CO 2 (g). Calcium oxide is a crucial ingredient in modern cement, and is also used as a chemical flux in smelting.
The theoretical heat (the standard enthalpy) of reaction required to make high-calcium lime is around 3.15 MJ per kg of lime, so the batch kilns were only around 20% efficient. The key to development in efficiency was the invention of continuous kilns, avoiding the wasteful heat-up and cool-down cycles of the batch kilns.
An example is when slaked lime (calcium hydroxide) is mixed into a thick slurry with sand and water to form mortar for building purposes. When the masonry has been laid, the slaked lime in the mortar slowly begins to react with carbon dioxide to form calcium carbonate (limestone) according to the reaction: Ca(OH) 2 + CO 2 → CaCO 3 + H 2 O.
To convert the oxide notation in LDH formula, the mass balance in the system has to respect the principle of the conservation of matter. Oxide ions (O 2−) and water are transformed into 2 hydroxide anions (OH −) according to the acid-base reaction between H 2 O and O 2− (a strong base) as typically exemplified by the quicklime slaking ...
The New York State Agricultural Experiment Station recipe for the concentrate suggests starting with 80 lb. of sulfur, 36 lb. of quicklime, and 50 gal. of water, equivalent to 19.172 kg of sulfur and 8.627 kg of calcium oxide per 100 litres of water. About 2.2:1 is the ratio (by weight) for compounding sulfur and quicklime; this makes the ...