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Consider the following reaction:
I2(g) + Cl2(g) ⇌ 2ICl(g) Kp= 81.9 at 25 ∘ C.
Calculate ΔGorxn for the reaction at 25 oC under each of the following conditions.
Part A: Standard conditions
Part B: At equilibrium
Part C:
PICl= 2.59 atm
PI2= 0.322 atm
PCl2= 0.221 atm
The Gibbs free energies and the equilibrium constant in relation to the pressure or concentration for the particular species when at particular temperature are correlated to one another according to the equation below. Any undetermined value can be discovered in the event that the other equation parameters are established.♦ Relevant knowledgeFree Energy
This is the reaction:
I2(g) + Cl2(g) ⇌ 2ICl(g)
Use the following formula to calculate the Gibbs-free energy change for the reaction.
ΔGrxn = ΔGo + RT lnQ
Here, ΔGo is Gibbs free energy change in standard conditions, R gas constant, T is temperature, and Q is reaction quotient.
Calculate ΔGo by using the following formula.
ΔGo = -RT lnK
Here K is the equilibrium constant for the reaction.
Below, calculate the reaction quotient.
Standard free energy change is the change in Gibbs free energy when one mole is made from its pure elements under normal conditions. Standard conditions are 1atm temperature and 298K temperatures.
At equilibrium, Gibbs free energy for a reaction will equal zero.
A)
ΔGo = -RT lnKp
ΔGo = -8.314 J/mol.K x 298K x ln(81.9)
= -8.314 J/mol.K x 298 x 4.405
= -10913 J/mol
= -10.91 kJ/mol
-10.91 kJ/mol is therefore standard Gibbs energy change free.
B)
At equilibriumGibbs free energy change is zero.
ΔGo = 0
(C)
Part A:
Standard Gibbs energy change is -10.91 kJ/mol.
Part B:
ΔGo = 0
Part C:
ΔGrxn = 0.353 kJ/mol