Given the following reaction 4HCl(g) + O2(g) → 2Cl2(g) + 2H2O(g) ΔH0 f, kJ/mol: HCl(g) (-92.31), H2O(g) (-241.8) S 0 , J/mol·K: HCl(g) (186.8), O2(g) (205), Cl2(g) (223.0), H2O(g) (188.7) a. Determine ΔH0 rxn (in kJ/mol) and ΔS 0 rxn (in J/mol·K) for the reaction below at 25oC using the given ΔH0 f and S0 values. b. Determine ΔG 0 (in kJ/mol) at 25oC and 1 atm and identify whether the reaction is spontaneous on the forward direction, spontaneous on the backward direction, or in equilibrium. c. Is the forward reaction spontaneous at lower temperatures, spontaneous at higher temperatures, spontaneous at all temperatures, or nonspontaneous at all temperatures? Explain briefly
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.
Given the following reaction
4HCl(g) + O2(g) → 2Cl2(g) + 2H2O(g)
ΔH0
f, kJ/mol: HCl(g) (-92.31), H2O(g) (-241.8)
S
0
, J/mol·K: HCl(g) (186.8), O2(g) (205), Cl2(g) (223.0), H2O(g) (188.7)
a. Determine ΔH0
rxn (in kJ/mol) and ΔS
0
rxn (in J/mol·K) for the reaction below at 25oC
using the given ΔH0
f and S0
values.
b. Determine ΔG
0
(in kJ/mol) at 25oC and 1 atm and identify whether the reaction is
spontaneous on the forward direction, spontaneous on the backward direction,
or in equilibrium.
c. Is the forward reaction spontaneous at lower temperatures, spontaneous at
higher temperatures, spontaneous at all temperatures, or nonspontaneous at all
temperatures? Explain briefly.
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