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.
The latent heat of fusion (∆H fus) of water at 0 °C is 6.025 KJ/mole and the molar heat capacities (Cp,m) of water are 75.3 for the liquid state and 37.7 for the solid state (or ice) - both in J/(K–mole). The Cp values can be taken to be independent of temperature. Considering these information and a kilogram of pure, liquid water at 25 °C, answer the questions that follow.
Calculate the ΔH (in KiloJoules) required to cool 1.0-Kg liquid water at 25°C to 0°C (in KJ). (Answer in three significant figures).
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