Slaking of lime

Calcium oxide CaO is called quicklime. Because of its interaction with water, the so-called slaked lime is obtained, and the process itself is slaking of lime.

Calcium oxide CaO is called quicklime. Because of its interaction with water, the so-called slaked lime is obtained, and the process itself is slaking of lime

To demonstrate the extinction of lime, pour a slurry of 25 g of calcium oxide on the asterite plate. From above, we make a hole in the test tube and pour water into it. Extinguishing of lime occurs according to the reaction:

+ 2 = ()2,

which is accompanied by a strong release of heat. In this case, excess water rises in the form of a column of water vapor. We hang the thermometer on the foot of the tripod so that its end is in the lime, which is extinguished, and observe the increase of temperature. This reaction is exothermic, goes with the liberation of 16 kcal (67 kJ) per mole.

Slaked lime is a fairly strong base, because of which the aqueous solution has an alkaline reaction. The solubility decreases with increasing temperature. Like all the bases, slaked lime reacts with acids to form the corresponding calcium salts:

()2 + H2SO4 = CaSO4 + 2H2O,

Calcium hydroxide reacts with carbon monoxide at a temperature of about 4000 C:

Ca(OH)2 + CO(t0) = CaCO3 + H2.

From the above, it can be concluded that quenching lime at first glance seems a simple chemical process.

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