5.25 Calculate ∆E and determine whether the process is endothermic or exothermic for the following cases: (a) q = 0.763 kJ and w = -840 J. (b) A system releases 66.1 kJ of heat to its surroundings while the surroundings do 44.0 kJ of work on the system.
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.
5.25 Calculate ∆E and determine whether the process is endothermic or exothermic for the following cases: (a) q = 0.763 kJ and w = -840 J. (b) A system releases 66.1 kJ of heat to its surroundings while the surroundings do 44.0 kJ of work on the system.
5.37 A gas is confined to a cylinder under constant atmospheric pressure, as illustrated in Figure 5.4. When the gas undergoes a particular
5.53 The specific heat of octane, C8H181l2, is 2.22 J>g@K. (a) How many J of heat are needed to raise the temperature of 80.0 g of octane from 10.0 to 25.0 °C? (b) Which will require more heat, increasing the temperature of 1 mol of C8H181l2 by a certain amount or increasing the temperature of 1 mol of H2O1l2 by the same amount?
5.63 Calculate the enthalpy change for the reaction P4O61s2+ 2 O21g2 ¡ P4O101s2 given the following enthalpies of reaction: P41s2+ 3 O21g2 ¡ P4O61s2 ∆H = -1640.1 kJ P41s2+ 5 O21g2 ¡ P4O101s2 ∆H = -2940.1 kJ
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