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Calcium hydroxide has a high enough pH to turn the phenolphthalein a vivid purplish-pink color, thus indicating the presence of water. Chemical pulping: Calcium oxide is used to make calcium hydroxide, which is used to regenerate sodium hydroxide from sodium carbonate in the chemical recovery at kraft pulp mills.
Magnesium has a mild reaction with cold water. The reaction is short-lived because the magnesium hydroxide layer formed on the magnesium is almost insoluble in water and prevents further reaction. Mg(s) + 2H 2 O(l) Mg(OH) 2 (s) + H 2 (g) [11] A metal reacting with cold water will produce a metal hydroxide and hydrogen gas.
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.
Calcium hydroxide is moderately soluble in water, as seen for many dihydroxides. Its solubility increases from 0.66 g/L at 100 °C to 1.89 g/L at 0 °C. [8] Its solubility product K sp of 5.02 × 10 −6 at 25 °C, [1] its dissociation in water is large enough that its solutions are basic according to the following dissolution reaction:
The reaction of calcium carbide with water, producing acetylene and calcium hydroxide, [5] was discovered by Friedrich Wöhler in 1862. CaC 2 + 2 H 2 O → C 2 H 2 + Ca(OH) 2 . This reaction was the basis of the industrial manufacture of acetylene, and is the major industrial use of calcium carbide.
The overall chemical reaction is: CO 2 + Ca(OH) 2 → CaCO 3 + H 2 O + heat (in the presence of water) 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 pozzolanic activity is a measure for the degree of reaction over time or the reaction rate between a pozzolan and Ca 2+ or calcium hydroxide (Ca(OH) 2) in the presence of water. The rate of the pozzolanic reaction is dependent on the intrinsic characteristics of the pozzolan such as the specific surface area, the chemical composition and ...
Calciothermic reactions are metallothermic reduction reactions (more generally, thermic chemical reactions) which use calcium metal as the reducing agent at high temperature. Calcium is one of the most potent reducing agents available, usually drawn as the strongest oxidic reductant in Ellingham diagrams , though the lanthanides best it in this ...