Many instant hot and cold packs (to soothe muscle pain and as first aid for sprains, respectively) function by the dissolution of solid salts in water at the time of need. Typical salts used are ammonium nitrate (NH4NO3) for cold packs and calcium chloride (CaCl2) for hot packs. Choose the TRUE statement. Select one: a.The dissolution of CaCl2 is endothermic, while that of NH4NO3 is exothermic. b.The dissolution of CaCl2 is exothermic, while that of NH4NO3 is endothermic. c.The dissolution of CaCl2 is endothermic, while that of NH4NO3 is athermic (ΔHsolution = 0). d.The dissolution of CaCl2 is athermic (ΔHsolution = 0), while that of NH4NO3 is exothermic.
Thermochemistry
Thermochemistry can be considered as a branch of thermodynamics that deals with the connections between warmth, work, and various types of energy, formed because of different synthetic and actual cycles. Thermochemistry describes the energy changes that occur as a result of reactions or chemical changes in a substance.
Exergonic Reaction
The term exergonic is derived from the Greek word in which ‘ergon’ means work and exergonic means ‘work outside’. Exergonic reactions releases work energy. Exergonic reactions are different from exothermic reactions, the one that releases only heat energy during the course of the reaction. So, exothermic reaction is one type of exergonic reaction. Exergonic reaction releases work energy in different forms like heat, light or sound. For example, a glow stick releases light making that an exergonic reaction and not an exothermic reaction since no heat is released. Even endothermic reactions at very high temperature are exergonic.
Many instant hot and cold packs (to soothe muscle pain and as first aid for sprains, respectively) function by the dissolution of solid salts in water at the time of need. Typical salts used are ammonium nitrate (NH4NO3) for cold packs and calcium chloride (CaCl2) for hot packs.
Choose the TRUE statement.
Select one:
a.The dissolution of CaCl2 is endothermic, while that of NH4NO3 is exothermic.
b.The dissolution of CaCl2 is exothermic, while that of NH4NO3 is endothermic.
c.The dissolution of CaCl2 is endothermic, while that of NH4NO3 is athermic (ΔHsolution = 0).
d.The dissolution of CaCl2 is athermic (ΔHsolution = 0), while that of NH4NO3 is exothermic.
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