A quantity of 1.435 g. of naphthalene (C10H8), a pungent smelling substance used in moth repellents, was burned in a constant-volume calorimeter. Consequently, the temperature of the water rose from 20.28°C to 25.95°C. if the heat capacity of the bomb plus water was 10.17 kJ/°C, calculate the heat of combustion of naphthalene on a molar basis; that is, find the molar heat of combustion. A 0.5786 g. of unknown substance is burned in a constant-volume bomb calorimeter that has a heat capacity of 1.674 kJ/°C. After the reaction, the temperature increased by 1.432°C. Find the heat given-off by the burning of the unknown in kJ/g.
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 quantity of 1.435 g. of naphthalene (C10H8), a pungent smelling substance used in moth repellents, was burned in a constant-volume calorimeter. Consequently, the temperature of the water rose from 20.28°C to 25.95°C. if the heat capacity of the bomb plus water was 10.17 kJ/°C, calculate the heat of combustion of naphthalene on a molar basis; that is, find the molar heat of combustion.
A 0.5786 g. of unknown substance is burned in a constant-volume bomb calorimeter that has a heat capacity of 1.674 kJ/°C. After the reaction, the temperature increased by 1.432°C. Find the heat given-off by the burning of the unknown in kJ/g.
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