What is the effect of adding quick lime to water?

• A. It cools down and settles
• B. It gets hot and forms hydrated lime
• C. It evaporates
• D. It dissolves immediately

Answer: (B)

Adding quick lime, also known as calcium oxide, to water causes an exothermic reaction, meaning it releases heat. This process not only raises the temperature of the mixture but also leads to the formation of hydrated lime, which is calcium hydroxide. When quick lime reacts with water, it undergoes a chemical change where it absorbs water and transforms into a more stable compound. This reaction is significant in water treatment processes, especially for adjusting pH levels and softening water.

The intense heat released during this reaction is a critical point, as it influences how quick lime is handled and applied in practical situations. The immediate formation of hydrated lime after the initial reaction plays a crucial role in its effectiveness for various applications in water treatment.