1 mol propane (C3H8) and stoichiometric amount of oxygen (O2) needed to combust propane was preheated to 400 K. After combustion, the products released are at 1500 K. The combustion products are H2O(l) and CO2(g). With 100% conversion was achieved, estimate the total heat released. Calculate the heat requirement for a reactor in combusting 1 mol of methane, CH4, with 25% excess air until the products reach a temperature of 1000 K. The reactants entered the reactor at 298.15 K and 100% conversion of methane is achieved. Assume air is approximately 21% O2 and 79% N2 and products are H2O(l) and CO2(g). Hint for both #1 and #2 – Combustion products at 298 K is CO2(g) and H2O(l). If the exiting temperature is above 373.15 K, H2O will leave as H2O(g). Therefore, you should account for the phase change of H2O(l) to H2O(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.
- 1 mol propane (C3H8) and stoichiometric amount of oxygen (O2) needed to combust propane was preheated to 400 K. After combustion, the products released are at 1500 K. The combustion products are H2O(l) and CO2(g). With 100% conversion was achieved, estimate the total heat released.
- Calculate the heat requirement for a reactor in combusting 1 mol of methane, CH4, with 25% excess air until the products reach a temperature of 1000 K. The reactants entered the reactor at 298.15 K and 100% conversion of methane is achieved. Assume air is approximately 21% O2 and 79% N2 and products are H2O(l) and CO2(g).
Hint for both #1 and #2 – Combustion products at 298 K is CO2(g) and H2O(l). If the exiting temperature is above 373.15 K, H2O will leave as H2O(g). Therefore, you should account for the phase change of H2O(l) to H2O(g).
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