CaO can be used as a drying agent. One such application occurs when water is added to dry concrete or cement. The reaction that occurs is CaO(s)+H2O(l)âCa(OH)2(s)

The product is commonly called slaked lime.

Assuming the commonly used standard-state temperature of 25âC, calculate ÎSuniv for this reaction using table from the table below.

Substance Sâ [J/(Kâmol)] ÎHâf (kJ/mol)
CaO(s) 39.9 â635.1
H2O(l) 69.9 â285.8
Ca(OH)2(s) 83.4 â986.1