A common laboratory reaction is the neutralization of an acid with a base. When 48.1 mL of 0.500 M HCl at 25.0°C is added to 60.3 mL of 0.500 M NaOH at 25.0°C in a coffee cup calorimeter (with a negligible heat capacity), the temperature of the mixture rises to 28.2°C. What is the heat of reaction per mole of NaCI (in kJ/mol)? Assume the mixture has a specific heat capacity of 4.18 J/(g-K) and that the densities of the reactant solutions are both 1.07 g/mL. Enter your answer to three significant figures in units of 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.
Given : Concentration of NaOH = 0.500 M
Volume of NaOH solution = 60.3 mL = 0.0603 L (since 1 L = 1000 mL)
Concentration of HCl = 0.500 M
Volume of HCl solution = 48.1 mL = 0.0481 L (since 1 L = 1000 mL)
Initial temperature of solutions = 25.0 oC
Final temperature of solution = 28.2 oC
Specific heat of solutions = 4.18 J/g.oC
And density of solutions = 1.07 g/mL.
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