When 4.20 g of solid NH4NO3 dissolves in 50.0 g of water at 26.8°C in a calorimeter, the temperature decreases to 20.9°C. The value of q for this reaction is 1.34 kJ. Calculate the enthalpy of solution (ΔH for the dissolution) in kilojoules per mole of NH4NO3 under the given conditions. (Assume that the specific heat of the aqueous solution is the same as water, 4.180 J/g·°C, and not sensitive to temperature over the temperature range.)
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.
When 4.20 g of solid NH4NO3 dissolves in 50.0 g of water at 26.8°C in a calorimeter, the temperature decreases to 20.9°C. The value of q for this reaction is 1.34 kJ. Calculate the enthalpy of solution (ΔH for the dissolution) in kilojoules per mole of NH4NO3 under the given conditions. (Assume that the specific heat of the aqueous solution is the same as water, 4.180 J/g·°C, and not sensitive to temperature over the temperature range.)
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