Endothermic vs Exothermic in regards to the system or the surroundings.

[ApexPredator]

I'm having some trouble identifying between endothermic and exothermic when it comes to the system and the surroundings. As an example from Destroyer Gen Chem

Ammonium nitrate will dissolve in water at 25°C, and a decrease in temperature is noted. Which of the following is true. The answer is +dS and +dH.

Explanation from destroyer: Since the temperature decreased, the reaction is endothermic; for heat has been absorbed

My confusion: In this example is water the system or the surroundings? How do tell if one is the system vs. the surrounding in these type of questions. Also who is absorbing heat system or surroundings?

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[jz123]

in this question, water is the surrounding and ammonium nitrate is the system. since the temperature of water is decreasing, which means the heat water lost is gained by the system, hence, for the system, it is considered endothermic.

Usually, dissolving something will increase entropy

hope this help you, let me know if you need further explanation.

 

[ApexPredator]

in this question, water is the surrounding and ammonium nitrate is the system. since the temperature of water is decreasing, which means the heat water lost is gained by the system, hence, for the system, it is considered endothermic.

Usually, dissolving something will increase entropy

hope this help you, let me know if you need further explanation.

Sorry for the late reply, and thank you for the clear explanation