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Endo and Exothermic Reactions

Procedure

First-aid cold and hot packs demonstrate spontaneous endothermic and exothermic reactions.
Break the water pouch and mix contents.

Reactions

Cold Pack

NH4NO3 (s) + H2O (l) --> NH4+ (aq) + NO3- (aq)

dH = +26.2 kJ/mole = 326 J/gm

Hot Pack

CaCl2 (s) + H2 O (l) --> Ca2+ (aq) + 2 Cl- (aq)

dH = -82 kJ/mole = -747 J/gm


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Last Updated: 5/23/02