Gibbs free energy and K for CaCO3 decomposition at 900K

[jin.cao]

Homework Statement

CaCO3 <-> CaO + CO2
At 900K, equilibrium pressure of CO2 is 0.0423 atm. Calculate Gibbs Free energy of Reaction and K.

Homework Equations

delta G = -RTlnK

The Attempt at a Solution

delta G = 5656.3 cal/mol
K = 0.0423

I have a feeling that this is incorrect
Could someone confirm/clarify for me

Thanks

 

[ron99]

I'm not sure what the pressure has to do with it..

 

[Mapes]

The equilibrium pressure of CO₂ is directly connected to the $\Delta G$ of the reaction. If the forward reaction is strongly favored, the pressure is higher, and vice versa.

 

[ron99]

ok, but does the pressure have anything to do with the calculations?

delta G = [sum(delta G formation, products) - sum(delta G formation, reactants)]

which can all be calculated from table values.

Then the equation:

delta G = -RTlnK can be used to find K

is this correct?