In an exothermic process, heat is released by the process to the surroundings. An example of an exothermic process is burning wood. An endothermic process requires the input of heat from the surroundings. An example of an endothermic process is boiling water. Which of the following is an endothermic process? detonation of an explosive melting ice burning paper the formation of helium on the sun freezing water
The Correct Answer and Explanation is:
The correct answer is: melting ice
Explanation:
In thermodynamics, chemical and physical processes are classified based on how they interact with heat. These are either exothermic (release heat) or endothermic (absorb heat).
An endothermic process is one that absorbs energy from its surroundings in the form of heat. This energy is required to break chemical bonds or change the state of matter in a way that increases molecular movement.
Let’s examine the options:
- Detonation of an explosive: This is an exothermic process. It releases a large amount of energy very quickly in the form of heat, light, and sound.
- Melting ice: This is an endothermic process. Ice requires the absorption of heat from its surroundings in order to change from solid to liquid. The energy goes into breaking the hydrogen bonds between water molecules in the solid phase so they can move more freely in the liquid phase. Even though the temperature remains at 0°C during the process, heat is still being absorbed. This makes it a classic example of an endothermic change.
- Burning paper: Like the detonation of an explosive, this is a combustion reaction and is highly exothermic. It releases heat and light as chemical bonds in cellulose and other materials are broken and new bonds form in the resulting gases.
- The formation of helium on the sun: This refers to nuclear fusion, a process where hydrogen nuclei combine to form helium. This reaction releases enormous amounts of energy and is the main source of the sun’s heat and light, making it exothermic.
- Freezing water: When water freezes, it releases heat into its surroundings. This is an exothermic process because the liquid water molecules lose energy and form a more ordered solid structure.
Therefore, melting ice is the only process among the options that requires the input of heat, making it endothermic.
