CaCl2 (MM = 110.98 g/mol) is used as road salt in the winter to minimize the accumulation of ice on roads. What is the ΔH°, in kJ/mol, for the dissolving of CaCl2 in water if the addition of 111 g of CaCl2 causes 889 g of water to increase in temperature by 19.6 °C? The specific heat capacity of water is 4.184 J/g°C. a) -82.0 kJ/mol b) 82.0 kJ/mol c) -72.9 kJ/mol d) 72.9 kJ/mol e) -9.10 kJ/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.
CaCl2 (MM = 110.98 g/mol) is used as road salt in the winter to minimize the accumulation of ice on roads. What is the ΔH°, in kJ/mol, for the dissolving of CaCl2 in water if the addition of 111 g of CaCl2 causes 889 g of water to increase in temperature by 19.6 °C? The specific heat capacity of water is 4.184 J/g°C.
a) -82.0 kJ/mol
b) 82.0 kJ/mol
c) -72.9 kJ/mol
d) 72.9 kJ/mol
e) -9.10 kJ/mol
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