A sample of solid biphenyl weighing 0.5260 g was ignited in a bomb calorimeter initially at 25 °C, producing a temperature rise of 1.910 K. Assuming a constant volume, calculate the AH of combustion of biphenyl. To properly determine the standard enthalpy of combustion for the solid biphenyl, the calorimeter was first calibrated. A 0.7750 g sample of benzoic acid (C6H3COOH, MW 122.1 g/mol)) was ignited under identical conditions and produced a temperature rise of 1.940 K. For benzoic acid, the internal energy combustion at constant volume, AU, is known to be -3226 kJ/mol. Calculate the calorimeter constant, in kJ/K.
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.
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