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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: Light384 on April 15, 2020, 10:49:47 PM

Title: Equilibrium Constant Calculation
Post by: Light384 on April 15, 2020, 10:49:47 PM
Hi! I need assistance with calculating the equilibrium constant of an overall reaction, yet whatever I try does not work.
The overall reaction is
2Cl2(g) + 10 NO(g) <-> 5N2(g) + 2Cl2O5(g)     with Kp=?

I am given:
2Cl2O5(g) <-> 5O2(g) + 2Cl2(g)    Kp1 =.095
2NO(g) <-> N2(g) + O2(g)      Kp2 =476

So I reversed the first equation given, thus I invert the respective equilibrium constant to get 1/.095; then I noticed that the overall reaction has 10 NO, thus I multiply the second given equation by 5, this requires me taking the equilibrium constant raised to the 5th power, thus I have 4765. Lastly, since I am adding the two equations together, I multiply the two equilibrium constants to get my overall equilibrium constant, which should be (4765)/(.095) however this is incorrect; what is my error?
Title: Re: Equilibrium Constant Calculation
Post by: Borek on April 16, 2020, 03:18:43 AM
Why do you think what you got is incorrect?

It looks OK to me.
Title: Re: Equilibrium Constant Calculation
Post by: Light384 on April 16, 2020, 03:46:22 AM
Quote from: Borek on April 16, 2020, 03:18:43 AM
Why do you think what you got is incorrect?

It looks OK to me.

My homework system (Canvas) keeps saying it is incorrect, I've tried entering the number in scientific notation (2.57 x 1014), tried typing out the actual number, yet it will not accept this value. I've checked with a few friends and they are also stuck on the same problem, we got the same answers.
Title: Re: Equilibrium Constant Calculation
Post by: Enthalpy on April 16, 2020, 07:19:29 AM
I doubt about Kp1 =.095. Cl2O5 is absolutely exotic, I doubt one obtains so much in an equilibrium mixture of O2 and Cl2.
Title: Re: Equilibrium Constant Calculation
Post by: Borek on April 16, 2020, 09:48:38 AM
Quote from: Light384 on April 16, 2020, 03:46:22 AM
My homework system (Canvas) keeps saying it is incorrect, I've tried entering the number in scientific notation (2.57 x 1014), tried typing out the actual number, yet it will not accept this value. I've checked with a few friends and they are also stuck on the same problem, we got the same answers.

All I can tell is that I don't see anything wrong with your approach and the result looks OK (in terms of the data given).
Title: Re: Equilibrium Constant Calculation
Post by: Light384 on April 17, 2020, 12:04:39 AM
Quote from: Borek on April 16, 2020, 09:48:38 AM
Quote from: Light384 on April 16, 2020, 03:46:22 AM
My homework system (Canvas) keeps saying it is incorrect, I've tried entering the number in scientific notation (2.57 x 1014), tried typing out the actual number, yet it will not accept this value. I've checked with a few friends and they are also stuck on the same problem, we got the same answers.

All I can tell is that I don't see anything wrong with your approach and the result looks OK (in terms of the data given).
Ah it was an error by my professor! He updated the class that he forgot to input an answer when setting up the assignment, so the assignment defaulted to the answer of 0. Just updating here!