A calorimeter contains 16.0 mLmL of water at 12.5 ∘C∘C . When 1.40 gg of XX (a substance with a molar mass of 75.0 g/molg/mol ) is added, it dissolves via the reaction X(s)+H2O(l)→X(aq)X(s)+H2O(l)→X(aq) and the temperature of the solution increases to 25.0 ∘C∘C . Calculate the enthalpy change, ΔHΔ�, for this reaction per mole of XX. Assume that the specific heat of the resulting solution is equal to that of water [4.18 J/(g⋅∘C)J/(g⋅∘C)], that density of water is 1.00 g/mLg/mL, and that no heat is lost to the calorimeter itself, nor to the surroundings. Express the change in enthalpy in kilojoules per mole to three significant figures.
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 calorimeter contains 16.0 mLmL of water at 12.5 ∘C∘C . When 1.40 gg of XX (a substance with a molar mass of 75.0 g/molg/mol ) is added, it dissolves via the reaction
X(s)+H2O(l)→X(aq)X(s)+H2O(l)→X(aq)
and the temperature of the solution increases to 25.0 ∘C∘C .
Calculate the enthalpy change, ΔHΔ�, for this reaction per mole of XX.
Assume that the specific heat of the resulting solution is equal to that of water [4.18 J/(g⋅∘C)J/(g⋅∘C)], that density of water is 1.00 g/mLg/mL, and that no heat is lost to the calorimeter itself, nor to the surroundings.
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