# Chemical Forums

## Chemistry Forums for Students => Physical Chemistry Forum => Topic started by: vola on May 06, 2021, 06:23:00 PM

Title: Calculating an equilibrium constant
Post by: vola on May 06, 2021, 06:23:00 PM
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
Title: Re: Calculating an equilibrium constant
Post by: Borek on May 06, 2021, 06:25:07 PM
Show what you did so far and why you think the answer is incorrect.
Title: Re: Calculating an equilibrium constant
Post by: vola on May 06, 2021, 06:39:04 PM
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
Title: Re: Calculating an equilibrium constant
Post by: mjc123 on May 07, 2021, 05:31:39 AM
You didn't forget the minus in ΔG° = -RTlnK, did you?