Multiple Choice
A chemical reaction has a enthalpy change of ΔH = -890.3 kJ/mol. Is this reaction exothermic or endothermic?
74
views
8. Thermochemistry
Endothermic & Exothermic Reactions
Multiple Choice
Which of the following processes is an example of an endothermic process?
A
Combustion of methane
B
Freezing of water
C
Melting of ice to liquid water
D
Condensation of water vapor
Verified step by step guidance1
Understand the definition of an endothermic process: it is a process that absorbs heat from the surroundings, meaning heat energy is taken in during the change.
Analyze each option in terms of heat flow:
- Combustion of methane releases heat (exothermic).
- Freezing of water releases heat as water changes from liquid to solid (exothermic).
- Melting of ice to liquid water requires heat input to break the solid structure (endothermic).
- Condensation of water vapor releases heat as gas changes to liquid (exothermic).
Identify that melting ice requires energy to overcome the forces holding the solid structure, so heat is absorbed from the surroundings.
Conclude that the melting of ice to liquid water is an example of an endothermic process because it involves absorption of heat.
Remember that phase changes from solid to liquid or liquid to gas are generally endothermic, while the reverse phase changes are exothermic.
Related Videos
Related Practice
