Enthalpy

[Twitch 22]

Why is it when you have something dissolve in water and the temperature decrease the enthalpy is greater than 0?? I thought a decrease in temperature meant that the reaction was exothermic thus an enthalpy less than 0....

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[Twitch 22]

anybody/??

 

[Thundercatz]

Because heat from the surrounding was absorbed into the system. If heat is absorbed into the system, then heat must of been lost from surrounding. Since heat is absorbed, the enthalpy is positive.

Hope that helps.