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A cold pack feels cold when the salt inside dissolves in water. How is this process classified?
AExothermic, because heat leaves the pack
BExothermic, because the pack loses its mass
CEndothermic, because the process takes in heat
DEndothermic, because the pack gives out heat
Answer & Solution
Correct answer: C. Endothermic, because the process takes in heat
1. A process that releases heat is exothermic, and one that absorbs heat is endothermic.
2. In a cold pack, water and a salt such as ammonium nitrate are brought together.
3. The dissolving process absorbs heat from its surroundings.
4. Your skin loses that heat, which is why the pack feels cold.
5. Burning acetylene in an oxyacetylene torch is the opposite case, an exothermic process.
_Source: OpenStax Chemistry (CC BY 4.0), Ch 5 "Thermochemistry", section 5.1 Energy Basics_
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