. The chemical reaction between quicklime
and water is characterised by:
A: evolution of hydrogen gas
B: formation of slaked lime precipitate
C: change in temperature of mixture
D: change in colour of the product
Quicklime or calcium oxide (CaO), when dissolved in water liberates a large amount of heat.
The reaction is so exothermic in nature that the heat produced can be used to ignite paper or to cook meals.
The reaction also produces a hissing sound and the product formed is calcium hydroxide or slaked lime (Ca(OH)2).
CaO(s) + H2O(1) → Ca (OH)2 (s) + 65.2kj /mol
quick lime = slaked lime
Even though slaked lime is formed and this can be a characterisation of the reaction,
the heat evolved is so high that it becomes the dominant factor for the characterisation of this reaction.
Hence, the reaction is characterized by a change in the temperature of the mixture.
The correct option is C: change in temperature of mixture.