Question

6. The reaction of quicklime, CaO, with water produces slaked lime, Ca(OH)2, which is widely used in the construction industry to make mortar and plaster. The reaction of quicklime and water is highly exothermic: CaO(s) + H2 O(l) ⟶ Ca(OH)2(s) ΔH = −350 kJ mol−1

Answer 1

1) Enthalpy of reaction per gram of quick lime or calcium oxide is -6.25 kJ/g.

2)
`4.730* 10^6`kilo Joules of energy is produced when 1 Tonn of slaked lime is produced.

Step-by-step explanation:

`CaO(s) + H_2O(l)\rightarrow Ca(OH)_2(s),\Delta H=-350 kJ/mol`

Enthalpy of reaction = ΔH = -350 kJ/mol

1 mole of calcium oxide = 56 g/mol

1 ) Enthalpy of reaction per gram of quick lime or calcium oxide:

`(\Delta H)/(56 g/mol)=(-350 kJ/mol)/(56 g/mol)=-6.25 kJ/g`

2) Mass of slake lime = 1 Tonn = 1,000,000 g

Moles of slaked lime =
`(1,000,000)/(74 g/mol)=13,513.51 mol`

According to reaction, on formation of 1 mol of slaked lime 350 kilo Joules of energy is produced.

Then energy produced when 13,513.51 moles of slaked lime is produced:

`350 kJ* 13,513.51 =4.730* 10^6 kJ`

`4.730* 10^6`kilo Joules of energy is produced when 1 Tonn of slaked lime is produced.