Which of the following is an exothermic process? A.Dilution of sulfuric acid B.Sublimation of dry ice C.Evaporation of water D.Melting of ice
Hint: We have to know that chemical reactions that liberate energy on moving towards the sides of a product are called exothermic reactions. The exothermic reactions which we can notice daily in our home are a combination of honey with calcium carbonate for sore throat. During the process, heat is given out and a soothing effect occurs.
Complete answer: We saw that when energy is given out in the form of heat, then it is exothermic reactions. Let us now identify the exothermic process among the given options. A.Dilution of sulfuric acid: In this reaction, acid is added to water to form a dilute solution of dilute sulfuric acid. Because of the formation of hydrogen bonds with water, energy is released by molecules and later, the water absorbs the same energy. So, this reaction is an exothermic one. Option (A) is correct. B.We know that the process of conversion of solid state of matter to gaseous form of water without going through the liquid state is sublimation. The sublimation reaction of dry ice is an endothermic reaction because heat energy is needed to finish the process. Option (B) is incorrect. C.We know that during the process of evaporation of water, water in liquid state to gaseous state. This reaction is endothermic because heat energy is needed to break the bond among the molecules of water. Option (C) is incorrect. D.We know that during the process of ice melting, ice changes from solid to liquid state and this is an endothermic reaction. Option (D) is incorrect. An example of an exothermic process is dilution of sulfuric acid.
Option (A) is correct.
Note: We have to know the dissolution process of acid; first acid is added to water. This is because there would be a sufficient amount of water molecules to take in the heat which is released at the time of reaction. But when water is added to acid, the reaction could result in explosion as it is highly exothermic. The reason for its exothermic nature is because large amounts of molecules would not be present for the absorption of heat, which is liberated.