Answer to Question #102403 in Chemistry for Popoola Farouq

Question

Calculate the standard free energy change for the reaction
H2 + I2 -------> 2HI at 127°c
Given that Kp= 41 atmosphere. ( R= 8.314 JK^-1 mol-1)

Answer 1

Task:

Calculate the standard free energy change for the reaction

H₂ + I₂ ---> 2HI at 127°C

Given that K_p = 41 atmosphere. ( R = 8.314 J K^-1 mol^-1)

Solution:

ΔG^o = standard free energy change.

The free energy change for a process taking place with reactants and products present under nonstandard conditions (ΔG) is related to the standard free energy change (ΔG°) according to this equation:

ΔG = ΔG^o + RTln(Q)

Q is the reaction quotient.

R = gas constant = 8.314 J K^-1 mol^-1

T = 127°C = 400 K.

For a system at equilibrium, Q = K_p and ΔG = 0, and the previous equation may be written as:

0 = ΔG^o + RTln(K_p) (at equilibrium)

ΔG^o =−RTln(K_p).

Hence,

ΔG^o = - 8.314 * 400 * ln(41) = -12349.85 J/mol = -12.35 kJ/mol.

Answer: ΔG^o = -12.35 kJ/mol.