Chemistry
DannyL
22

Which physical change is endothermic? (1) CO2(s)-->CO2(g) (3) CO2(g)-->CO2(l) (2) CO2(l)-->CO2(s) (4) CO2(g)-->CO2(s)

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(2) Answers
coolkid214

Reaction 1 is Sublimation which is an endothermic reaction.

ufnwish73

The correct answer is (1) CO2(s)-->CO2(g). CO2(s) needs energy to break its bond to become CO2(g). Therefore, we have to provide CO2(s) with energy/ heat and that's why (1) is an endothermic reaction. Hope this helps~

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