Consider the following reaction: C2H4(g) + H2O(g) ⇌ C2H5OH(g) ΔHo = -45.8 kJ/mol At 298K the equilibrium constant, KP, for this reaction is 28.5. What is ΔG for this reaction at 298K under the following conditions: p(C2H4) = p(H2O) = p(C2H5OH) = 3.0 atm?

ΔG = 2721.891 J/mol

Explanation:

∴ ΔH°rxn = - 45.8 KJ/mol

∴ Kp = 28.5

If p(C2H4) = p(H2O) = p(C2H5OH) = 3.0 atm ⇒ ΔG°rxn = ?

⇒ Kp = (PC2H5OH/P*) / (PC2H4/P*)(PH2O/P*)

∴ P* = 1 atm

⇒ Kp = (3 atm) / (3 atm)(3 atm) = 0.33

⇒ Ln Kp = - ΔG/RT

⇒ ΔG = - RT LnKp

∴ T = 298 K

∴ R  = 8.314 J/mol.K

⇒ ΔG = - ((8.314 J/mol.K)(298 K)) Ln(0.33)

⇒ ΔG = 2721.891 J/mol

adding or remove a gaseous reactant or product changes the concentrations. if the concentration of reactant or product is increased, the system will shift away from the side in which concentration was increased (i.e. if the concentration of reactants is increased, the system will shift toward the products. if more products are added, the system will shift to form more reactants). conversely, if the concentration of reactant or product is decreased, the system will shift toward the side in which concentration was decreased (i.e. if reactants are removed, the system will shift to form more reactants. if the concentration of products is decreased, the equilibrium will shift toward the products).

explanation: