13.4gof NH4Clis dissolved in 150mLof water in a coffee-cup calorimeter, and the temperature of the solution decreases from 24.80°C to 18.95°C. (a) Calculate the enthalpy change for the dissolution ofthis sample ofNH4ClinJ.
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.
13.4gof NH4Clis dissolved in 150mLof water in a coffee-cup calorimeter, and the temperature of the solution decreases from 24.80°C to 18.95°C.
(a) Calculate the enthalpy change for the dissolution ofthis sample ofNH4ClinJ.
(b) What would be the enthalpy change for dissolving one mole of NH4Cl in kJ/mol?Note that the specific heat capacity of water is 4.186J/g·Kand its density is 1.00 g/mL. Remember that the heat gained by the water is heat that is lost by the system.
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