Solid calcium oxide reacts vigorously with water to form calcium hydroxide accompanied by liberation of heat.

Question

Solid calcium oxide reacts vigorously with water to form calcium hydroxide accompanied by the liberation of heat. This process is called the slaking of lime. Calcium hydroxide dissolves in water to form its solution called lime water. Which among the following is (are) true about the slaking of lime and the solution formed? 

(i) It is an endothermic reaction 

(ii) It is an exothermic reaction 

(iii) The pH of the resulting solution will be more than seven 

(iv) The pH of the resulting solution will be less than seven 

(a) (i) and (ii) 

(b) (ii) and (iii) 

(c) (i) and (iv) 

(d) (iii) and (iv)

Answer 1

The correct option is (b) (ii) and (iii) 

• Slaking, the process of turning the traditional building material lime from calcium oxide (burnt lime or quicklime) into calcium hydroxide (slaked lime, slack lime, limewater, pickling lime or hydrated lime).
• Its exothermic process and as calcium hydroxide is basic so pH will be greater than 7.