Endo and Exothermic Reactions

Materials

6-8 Cold Packs

6-8 Hot Packs

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