2 HIg) + Cl2(g) 2 HCl(g) + I2(s)?

Question

2 HIg) + Cl2(g) 2 HCl(g) + I2(s)

Calculate the following values for the reaction above.

(a) H° = kJ
(b) S° = J/K
(c) G° = kJ

(d) Calculate G° at 25° using the Gibbs-Helmholtz equation.
kJ

(e) Describe the reaction in the forward direction. (Select all that apply.)

endothermic
exothermic
entropy increases
entropy decreases
spontaneous
nonspontaneous

Answer 1

delta Hºrxn =2Hº (HCL)+Hº(I2) -2Hº(HI)-H(CL2)
=2(-92.31)+0-2(26.48)+0
=-237.58KJ/mol(endothermic rxn)

delta Sº= 2Sº(HCL)+Sº(I2) -2Sº(HI)-Sº(CL2)
=2(186.91)=116.135 -2(206.59) -223.07
=-146.3J/K.mol(entropy decrease)

delta G ºrxn =2Gº(HCL)+Gº(I2) -2Gº(HI)-Gº(CL2)
=2(-95.3) -2(1.7)
=194KJ/mol (non spontaneous)

Answer 2

You're going to need to use values, most likely for the enthalpy of formation and for the entropy of the various products and reactants. Once you calculate delta H and delta S for the reaction, you can calculate DG. I'm guessing that there is either a table in your chem text or in the appendix that will have everything you need...