Which event is an example of an exothermic reaction?
a
evaporation
b
melting ice
c
decomposition
d
combustion
d
combustion
The correct answer is d) combustion.
Combustion is an example of an exothermic reaction because it releases heat and energy.
The event that is an example of an exothermic reaction is option d, combustion. To determine this, let's understand what exothermic reactions are and then analyze each option.
Exothermic reactions are chemical reactions that release energy in the form of heat. During such reactions, the products have lower energy than the reactants, resulting in a net release of energy. Now, let's analyze the options:
a. Evaporation: Evaporation refers to the process in which a liquid changes into a gas. It is not an example of an exothermic reaction because it requires energy input in the form of heat to break the intermolecular forces that hold the liquid molecules together.
b. Melting ice: Melting ice is also not an example of an exothermic reaction. It is a phase change in which solid ice changes into liquid water. Similar to evaporation, melting ice requires energy input to break the intermolecular forces between the ice molecules.
c. Decomposition: While decomposition reactions can be both exothermic or endothermic depending on the specific reaction, it is not a specific example of an exothermic reaction in this context without further information.
d. Combustion: Combustion is the process of burning, where a fuel reacts with oxygen to produce carbon dioxide, water vapor, and release heat and light. This reaction is an example of an exothermic reaction because it releases energy in the form of heat and light.
Therefore, option d, combustion, is the correct answer as it represents an example of an exothermic reaction.