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The chemical reaction between quicklime and water to form slaked lime is characterized by
A change in colors
The formation of a precipitates
A decrease in temperature
A rise in temperature
None of the above
A rise in temperature
The reaction between quicklime (calcium oxide) and water is an exothermic reaction, which releases a significant amount of heat. This increase in kinetic energy of the molecules results in a measurable rise in the temperature of the reaction vessel.
The reaction between quicklime (calcium oxide) and water is an exothermic reaction, which releases a significant amount of heat. This increase in kinetic energy of the molecules results in a measurable rise in the temperature of the reaction vessel.
Think of it like a hand warmer packet or a self-heating meal; as soon as you introduce water, the internal chemical energy is converted directly into heat that you can feel on the container wall.
EXO = Exit (Heat exits the system).
CaO(s)+H2тАЛO(l)тЖТCa(OH)2тАЛ(aq)+╬ФH
╬ФH<0 (indicating exothermic process)
The chemical process, known as slaking, involves the hydration of calcium oxide (CaO). The reaction CaO(s)+H2тАЛO(l)тЖТCa(OH)2тАЛ(aq)+Heat is highly exothermic. The breaking of the strong ionic lattice of CaO and the formation of the Ca(OH)2тАЛ bond release more energy than is consumed, leading to the evolution of thermal energy.
Quicklime is chemically known as calcium oxide.
Slaked lime is chemically known as calcium hydroxide.
Exothermic reactions result in a net release of energy to the surroundings.
Used in white-washing walls as it absorbs CO2тАЛ to form a hard layer of calcium carbonate.
The reaction can be violent if large amounts of quicklime are added to a small amount of water suddenly.
Whitewashing of walls
Water treatment and pH adjustment
The resulting solution of calcium hydroxide is also known as lime water.
Option A is incorrect because no characteristic color change occurs; the mixture remains milky white.
Option B is incorrect because slaked lime is partially soluble in water, forming a suspension rather than a precipitate.
Option C is incorrect because exothermic reactions increase energy, not decrease it.
D is correct тАФ The reaction is exothermic, leading to a significant increase in the temperature of the reaction mixture.
Always check the enthalpy change (╬ФH) sign in reactions; a negative ╬ФH always signifies heat release, which is a common favorite for examiners in thermodynamics-related questions.
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