Which chemical or physical change is an exothermic process?
A. the baking of cookies
B. the combustion of gasoline
C. the evaporation of water from a pool
D. the cold pack reaction $\left( NH _4 NO _3+ H _2 O +\right.$ heat $\rightarrow NH _4 OH + HNO _3$ )
Answer (1)
Baking cookies, evaporation of water, and cold pack reactions absorb heat and are endothermic.
Combustion of gasoline releases heat.
Therefore, the exothermic process is t h eco mb u s t i o n o f g a so l in e .
Explanation
Analyze each option Let's analyze each option to determine whether it releases or absorbs heat. An exothermic process releases heat, while an endothermic process absorbs heat.
Identify the exothermic process
The baking of cookies: Baking requires heat to be added, so it is an endothermic process.
The combustion of gasoline: Combustion (burning) releases heat and light, so it is an exothermic process.
The evaporation of water from a pool: Evaporation requires heat for the water to change from liquid to gas, so it is an endothermic process.
The cold pack reaction ( N H 4 N O 3 + H 2 O + heat → N H 4 O H + H N O 3 ): This reaction absorbs heat, as indicated by 'heat' being a reactant, so it is an endothermic process.
Conclusion Based on the analysis, the combustion of gasoline is the only exothermic process among the given options.
Examples
Understanding exothermic reactions is crucial in many real-world applications. For instance, the combustion of fuels like gasoline in car engines releases energy that powers the vehicle. Similarly, the burning of natural gas in home furnaces provides heat during winter. Exothermic reactions are also used in the production of explosives, where a large amount of energy is rapidly released, creating a powerful explosion. Recognizing and controlling exothermic processes is essential for safety and efficiency in various industrial and everyday scenarios.
