Reaction of Calcium Oxide and Water

Problem The conversion reaction of quicklime or caustic lime (CaO) to slaked or hydrated lime (Ca (OH)2), is historically an important process. After limestone CaC03 is heated at a temperature of about 1000°C, calcium oxide CaO is produced this calcium oxide reacts with water to form calcium hydroxide Ca (OH)2 this can be used to regenerate limestone again by the reaction with carbon dioxide forming once again calcium carbonate CaC03 ( lime circulation ). 

From the chemical point of view, the reaction of calcium oxide with water is a classic acid-base reaction according to the Broensted theory oxide ions are base particles and take protons from water molecules - in this case, water 

Material Erlenmeyer flask, thermometer pieces of calcium oxide (fresh), water. 

Procedure Place several pieces of calcium oxide in an Erlenmeyer flask, add a little water, and measure the maximum temperature with a thermometer. 

Observation It takes about half a minute for the reaction to begin. The mixture fizzes, the beaker mists up, and the temperature rises to 100°C. The formed calcium hydroxide shows a larger volume than the original amount of calcium oxide - however both substances are white. 

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