[vola]

 For the same reaction, the standard Gibbs
energy of reaction at 2000K is +135.2 kJmol−1
. Suppose that
steam at 200 kPa is passed through a furnace tube at that
temperature. Calculate the mole fraction of O2 present in the
output gas stream.

i cant find the right result

[Borek]

Show what you did so far and why you think the answer is incorrect.

[vola]

The standard Gibbs energy of reaction for the decomposition of water

H2O(g) --> H2(g) + 1/2 O2(g)

is 135.2 kJ/mol at 2000K.  Suppose that steam at 200 kPa is passed through a furnace tube at 2000K. Calculate the mole fraction of H2(g) in the output gas stream.
sorry, the full question is like that.
 
First I found k=(p/Po)^1/2* alpha3/2 / 2^1/2 ( 1 - alpha )
 using ice table and k value using delta G=RTlnk but I can not understand where should I put the given pressure

[mjc123]

You didn't forget the minus in ΔG° = -RTlnK, did you?