The value of ΔS°rxn for the reaction is -310.9JK⁻¹ .
WHAT IS ΔS IN A REACTION ?
∆S is the change in entropy (disorder) from reactants to products. R is the gas constant (always positive) T is the absolute temperature (Kelvin, always positive) What it means: If ∆H is negative, this means that the reaction gives off heat from reactants to products.
General expression for ΔS°rxn of a chemical reaction is as follows:
[tex]\Delta S^o_{rxn} = \sum m S^o_{(products)} - \sum n S^o_{(reactants)}[/tex]
Here, m, n represent the stoichiometry coefficients of each product and reactant.
For the reaction,
2NO(g) + 5H₂(g) → 2NH₃(g) + 2H₂O(g)
The expression for ΔS°rxn is as follows:
[tex]\Delta S^o_{rxn} = [(2mol)(S^o_{NH_3 (g)}) + (2mol)(S^o_{H_2 O (g)})] [(2mol)(S^o_{NO (g)}) + (5mol)(S^o_{H_2 (g)})][/tex]
From the appendix B, the standard values for entropy S° for NH₃(g) is 193 J mol⁻¹ K⁻¹, for H₂O(g) is 188.72 J K⁻¹ mol⁻¹, for NO(g) the value of S° is 210.65 J mol⁻¹ K⁻¹, and S° for H₂(g) is 130.6 J mol⁻¹K⁻¹.
Substitute the standard values of entropy in the expression for ΔS°rxn.
[tex]\Delta S^o_{rxn} = [(2mol)(193Jmol^{-1}K^{-1}) + (2mol)(188.72Jmol^{-1}K^{-1})] -[/tex]
[tex][(2mol)(210.65Jmol^{-1}K^{-1}) + (5mol)(130.6Jmol^{-1}K^{-1})][/tex]
[tex]= [763.44 JK^{-1}] - [1074.3 JK^{-1}]\\= - 310.9 JK^{-1}[/tex]
Thus, the value of ΔS°rxn for this reaction is - 310.9 JK⁻¹.
Lear more about ΔS IN A REACTION are:
https://brainly.com/question/19299818
#SPJ4
