Consider the following chemical equation. CH4(g) + 2O2(g) à CO2(g) + 2H2O(l) Using the values in the table, calculate the standard enthalpy change. CO2(g) = -393.5 kJ/mol O2(g) = 0 kJ/mol H2O(g) = -241.8 kJ/mol H2O(l) = -285.8 kJ/mol CH4(g) = -74.85 kJ/mol SO2(g) = -296.4 kJ/mol SO3(g) = -395.2 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.
5. Consider the following chemical equation.
CH4(g) + 2O2(g) à CO2(g) + 2H2O(l)
Using the values in the table, calculate the standard enthalpy change.
CO2(g) = -393.5 kJ/mol
O2(g) = 0 kJ/mol
H2O(g) = -241.8 kJ/mol
H2O(l) = -285.8 kJ/mol
CH4(g) = -74.85 kJ/mol
SO2(g) = -296.4 kJ/mol
SO3(g) = -395.2 kJ/mol
Enthalpy of formation of one mole of carbon dioxide = -393.5 KJ/mol
Enthalpy of formation of one mole of liquid water = -285.8 KJ/mol
Enthalpy of formation of two moles of liquid water = -285.8 × 2 = -571.6 KJ/mol
Enthalpy of formation of product = -571.6 – 393.5 = -965.1 KJ/mol
Step by step
Solved in 3 steps
