DAT DESTROYER #22 solubility/thermodynamics

[shiftypoptart]

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How is this true?

"When solid NH4NO3 is dissolved in water at 25C, the solution temperature decreases. This reaction is endothermic."

The explanation in the back says: since the solution got colder, heat was absorbed, thus, the reaction is endothermic.

For some reason this doesn't make sense in my head, how is it that heat got absorb yet the solution got colder. I always thought that when heat got absorbed temperature increased. Someone explain this cause its bugging me =/.

 

[whathashizzyDDS]

Remember, everything is in terms of the system. In this case the solid, sucked up heat from the surroundings (for lack of better word) and caused the surrounding (solution) to become cooler..

The solid requires heat to break bonds, thus, being endothermic

Hope this helps!

 

[vindicate]

endothermic

heat + a -> b + c


exothermic

a + b -> c + heat


endothermic: heat is a reageant.
you absorb heat to make products, making final product relatively cooler.

 

[shiftypoptart]

Ahhh its makes sense now. Thanks for your help! Especially the part of the molecule sucking up heat lol.