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H 2 (g) + Cl 2 (g) -------> 2 HCl (g) Appendix 4: H2 (g): H o = 0, S o = 131 J/K

ID: 511499 • Letter: H

Question

H2 (g) + Cl2 (g) -------> 2 HCl (g)
Appendix 4: H2 (g): Ho = 0, So = 131 J/K * mol, Go = 0. Cl2 (g): Ho = 0, So = 223 J/K * mol, Go = 0. HCl (g): Ho = -92 Kj/mol, So = 187 J/K * mol, Go = -95 Kj/mol

a) Calculate Ho, So, Go and equilibrium constant K (at 298 K) using data in Appendix 4 of Zumdahl textbook

b) If H2 (g), Cl2 (g), and HCl (g) are placed in a flask such that the pressure of each gas is 1 atm, in which direction will the system will shift to reach equilibrium at 25oC?

Explain please.
Thanks!

Explanation / Answer

a)H(g) +cl2(g)-› 2HCL(g)

Given data

H2 (g): Ho=0, So = 131 J/K * mol, Go = 0. Cl2 (g): Ho = 0, So = 223 J/K * mol, Go = 0. HCl (g): Ho = -92 Kj/mol, So = 187 J/K * mol, Go = -95 Kj/mol

DeltaH= DeltaH(product)-Delta H(reactant)

=2*(-92)-0-0=184 KJ/mol

Delta S= Delta S(product)- Delta S(reactant)

=2*187-223-131 =20J/K mol

Delta G=Delta G(product)- Delta G(reactant)

=-95*2-0-0= -190KJ/mol

Equilibrium constant k

Delta G= -RT lnk

k= e^-(DeltaG/RT)

k= e^-(-190*10^3/8. 314*298)

k =2. 0192*10^33

b) when H2g, cl2g and HClg placed in a flask with 1atm pressure, the system will shift to forward direction and will occur mostly to the completion of reaction. It will use almost all the reactants or exhaust due to high value of k.