Which of the following reactions will have the largest value of K at 298 K? A) CaCO3(s) → CaO(s) + CO2(g) ΔG° =+131.1 kJ B) 2 Hg(g) + O2(g) → 2 HgO(s) ΔG° = ‒180.8 kJ C) 3 O2(g) → 2 O3(g) ΔG° = +326 kJ D) Fe2O3(s) + 3 CO(g) → 2 Fe(s) + 3 CO2(g) ΔG° = ‒28.0 kJ

Respuesta :

Answer :

(a) The value of 'K' for the reaction is [tex]1.05\times 10^{-23}[/tex]  

(b) The value of 'K' for the reaction is [tex]4.93\times 10^{31}[/tex]

(c) The value of 'K' for the reaction is [tex]7.17\times 10^{-58}[/tex]

(d) The value of 'K' for the reaction is [tex]8.09\times 10^{4}[/tex]

Explanation :

The relation between the equilibrium constant and standard Gibbs free energy is:

[tex]\Delta G^o=-RT\times \ln K[/tex]

where,

[tex]\Delta G^o[/tex] = standard Gibbs free energy

R = gas constant = 8.314 J/K.mol

T = temperature = 298 K

K = equilibrium constant

Now we have to calculate the value of 'K' for the following reactions.

(a) [tex]CaCO_3(s)\rightarrow CaO(s)+CO_2(g)[/tex]    [tex]\Delta G^o=+131.1kJ=+131100J[/tex]

[tex]\Delta G^o=-RT\times \ln K[/tex]

[tex]+131100J=-(8.314J/K.mol)\times (298K)\times \ln K[/tex]

[tex]K=1.05\times 10^{-23}[/tex]

Thus, the value of 'K' for the reaction is [tex]1.05\times 10^{-23}[/tex]

(b) [tex]2Hg(g)+O_2(g)\rightarrow 2HgO(s)[/tex]    [tex]\Delta G^o=-180.8kJ=-180800J[/tex]

[tex]\Delta G^o=-RT\times \ln K[/tex]

[tex]-180800J=-(8.314J/K.mol)\times (298K)\times \ln K[/tex]

[tex]K=4.93\times 10^{31}[/tex]

Thus, the value of 'K' for the reaction is [tex]4.93\times 10^{31}[/tex]

(c) [tex]3O_2(g)\rightarrow 2O_3(g)[/tex]    [tex]\Delta G^o=+326kJ=+326000J[/tex]

[tex]\Delta G^o=-RT\times \ln K[/tex]

[tex]+326000J=-(8.314J/K.mol)\times (298K)\times \ln K[/tex]

[tex]K=7.17\times 10^{-58}[/tex]

Thus, the value of 'K' for the reaction is [tex]7.17\times 10^{-58}[/tex]

(d) [tex]Fe_2O_3(s)+3CO(g)\rightarrow 2Fe(s)+3CO_2(g)(s)[/tex]    [tex]\Delta G^o=-28.0kJ=-28000J[/tex]

[tex]\Delta G^o=-RT\times \ln K[/tex]

[tex]-28000J=-(8.314J/K.mol)\times (298K)\times \ln K[/tex]

[tex]K=8.09\times 10^{4}[/tex]

Thus, the value of 'K' for the reaction is [tex]8.09\times 10^{4}[/tex]