Question

Solid Calcium oxide reacts vigorously with water to form Calcium hydroxide accompanied by the liberation of heat. From the information given above it may be concluded that this reaction

• A. is endothermic and pH of the solution formed is more than 7.
• B. is exothermic and pH of the solution formed is 7.
• C. is endothermic and pH of the solution formed is 7.
• D. is exothermic and pH of the solution formed is more than 7.

Answer 1

The Correct Option is D

Step 1: Understanding the reaction:
The given reaction involves the combination of solid calcium oxide (CaO) with water (H₂O) to form calcium hydroxide (Ca(OH)₂), accompanied by the liberation of heat.
The reaction is as follows:

CaO(s) + H2O(l) → Ca(OH)2(aq) + heat

Step 2: Analyzing the nature of the reaction:
The release of heat during the reaction indicates that it is an exothermic reaction. In exothermic reactions, energy is released to the surroundings, which leads to an increase in temperature.

Step 3: Identifying the pH of the solution:
Calcium hydroxide (Ca(OH)₂) is a strong base when dissolved in water. It dissociates to form hydroxide ions (OH^–), which increases the pH of the solution. Since the pH scale ranges from 0 to 14, with 7 being neutral, a base has a pH greater than 7.

Step 4: Conclusion:
Based on the given information, we can conclude that the reaction is exothermic and the pH of the solution formed is more than 7 due to the formation of a strong base, calcium hydroxide.