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Each mole of CO 2 (44 g) reacts with one mole of calcium hydroxide (74 g) and produces one mole of water (18 g). The reaction can be considered as a strong-base-catalysed, water-facilitated reaction. [5] The reaction mechanism of carbon dioxide with soda lime can be decomposed in three elementary steps: 1) () (CO 2 dissolves in water – slow ...
As lime in the form of limewater is added to raw water, the pH is raised and the equilibrium of carbonate species in the water is shifted. Dissolved carbon dioxide (CO 2) is changed into bicarbonate (HCO − 3) and then carbonate (CO 2-3). This action causes calcium carbonate to precipitate due to exceeding the solubility product.
Rain water contains dissolved carbon dioxide taken from the atmosphere. Some of the dissolved carbon dioxide reacts with the water to form carbonic acid, which remains in solution. Minerals containing calcium and magnesium form soluble bicarbonates when exposed to carbonic acid. Water containing these minerals is known as "hard water".
Calcium hydroxide reacts with hydrochloric acid to give calcium hydroxychloride and then calcium chloride. In a process called sulfation, sulphur dioxide reacts with limewater: Ca(OH) 2 (aq) + SO 2 (g) → CaSO 3 (s) + H 2 O (l) Limewater is used in a process known as lime softening to reduce water hardness. It is also used as a neutralizing ...
This is accomplished by heating the material to above 825 °C (1,517 °F), [6] [7] a process called calcination or lime-burning, to liberate a molecule of carbon dioxide (CO 2), leaving quicklime behind. This is also one of the few chemical reactions known in prehistoric times. [8] CaCO 3 (s) → CaO(s) + CO 2 (g)
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.
Other strong bases such as soda lime, sodium hydroxide, potassium hydroxide, and lithium hydroxide are able to remove carbon dioxide by chemically reacting with it. In particular, lithium hydroxide was used aboard spacecraft , such as in the Apollo program , to remove carbon dioxide from the atmosphere.
Carbonatation is a slow process that occurs in concrete where lime (CaO, or Ca(OH) 2 ) in the cement reacts with carbon dioxide (CO 2) from the air and forms calcium carbonate. The water in the pores of Portland cement concrete is normally alkaline with a pH in the range of 12.5 to 13.5.