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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 ...
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.
Instead of treating the remaining solution with lime, carbon dioxide and ammonia are pumped into the solution, then sodium chloride is added until the solution saturates at 40 °C. Next, the solution is cooled to 10 °C. Ammonium chloride precipitates and is removed by filtration, and the solution is recycled to produce more sodium carbonate.
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)
A solution or suspension of calcium hydroxide is known as limewater and can be used to test for the weak acid carbon dioxide. The reaction Ca(OH) 2 + CO 2 ⇌ Ca 2+ + HCO − 3 + OH − illustrates the basicity of calcium hydroxide. Soda lime, which is a mixture of the strong bases NaOH and KOH with Ca(OH) 2, is used as a CO 2 absorbent.