Assume you are interested in exploring the use of ammonium nitrate (NH4NO3) as the active ingredient in an inexpensive home-made cold pack. You decide that a practical cold pack should be able to depress the temperature of 1 kg of human muscle tissue by 5 oC. Now you need to know the amount of NH4NO3 required to achieve this. Ammonium nitrate is a highly water soluble solid. You believe the enthalpy of dissolution for NH4NO3 must be determined. To this end, you add 2.339
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.
Assume you are interested in exploring the use of ammonium nitrate (NH4NO3) as the active ingredient in an inexpensive home-made cold pack. You decide that a practical cold pack should be able to depress the temperature of 1 kg of human muscle tissue by 5 oC. Now you need to know the amount of NH4NO3 required to achieve this. Ammonium nitrate is a highly water soluble solid. You believe the enthalpy of dissolution for NH4NO3 must be determined. To this end, you add 2.339 g of NH4NO3 to 99.7 mL of water at 23.7 °C in a constant-pressure calorimeter and close the calorimeter. The temperature of the water decreases to a minimum of 21.9 °C.
1a. Assume the density and specific heat of water is 1.00 g/mL and 4.184 J/g °C, respectively. Using the data above, determine the for ammonium nitrate in water. Assume the heat capacity of the calorimeter is negligible.
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