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