A coffee cup calorimeter contains 143 g of water at 22.5 °C. A 12 g sample of NaCl is added to the water in the calorimeter. After the solid has dissolved, the temperature of the water is 21.6 °C. Calculate the enthalpy for dissolving sodium chloride in kJ/mol of NaCl. Assume that no heat is lost to the calorimeter or the surroundings and that the specific heat of the solution is the same as that of pure water, 4.184 J/g°C. The molar mass of NaCl is 58.44 g/mol.
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.
A coffee cup calorimeter contains 143 g of water at 22.5 °C. A 12 g sample of NaCl is added to the water in the calorimeter. After the solid has dissolved, the temperature of the water is 21.6 °C. Calculate the enthalpy for dissolving sodium chloride in kJ/mol of NaCl. Assume that no heat is lost to the calorimeter or the surroundings and that the specific heat of the solution is the same as that of pure water, 4.184 J/g°C. The molar mass of NaCl is 58.44 g/mol.
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