Equilibrium Constant Calculation

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Discussion Overview

The discussion revolves around the calculation of the equilibrium constant for a chemical reaction, including the equilibrium concentrations of reactants and products at a specified temperature. Participants are engaged in correcting and refining the arithmetic involved in the calculation.

Discussion Character

  • Homework-related
  • Mathematical reasoning

Main Points Raised

  • The initial calculation of the equilibrium constant was presented, but the poster indicated that their answer was incorrect.
  • One participant pointed out an arithmetic error in the calculation, questioning how the initial result of 2.9 x 10-5 was obtained.
  • The original poster clarified that they rounded their answer to two significant figures from a more precise value of 0.000028836.
  • Another participant noted that the value provided was only the numerator of the equilibrium constant calculation.
  • The original poster acknowledged the mistake and provided a new answer of 500640625, which was met with humor regarding the magnitude of the error.
  • One participant confirmed that the arithmetic error was significant, indicating it was more than a rounding error.

Areas of Agreement / Disagreement

Participants generally agree that there was a significant arithmetic error in the original calculation, but the discussion remains focused on correcting the calculation rather than reaching a consensus on the final value.

Contextual Notes

The discussion highlights the importance of careful arithmetic in equilibrium constant calculations, but does not resolve the final value of the equilibrium constant due to the ongoing corrections.

Spallation
Messages
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Determine the equilibrium constant, my working is below:

Equilibrium reaction:
[PLAIN]http://img34.imageshack.us/img34/5106/reactiondy.jpg

At 730 oC the equilibrium concentrations of reactants and products are:

[H2 (g) ] / mol dm-3 : 2.40 x 10-7

[Cl2 (g)] / mol dm-3 : 2.40 x 10-7

[HCl (g)] / mol dm-3: 5.37 x 10-3

[PLAIN]http://img163.imageshack.us/img163/4485/equationconstant.jpg




My answer is wrong but I don't know why, I must have missed something out. Thanks for any explanations I receive.
 
Last edited by a moderator:
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Welcome to PF!

Hi Spallation! Welcome to PF! :smile:

Your arithmetic is wrong … how did you get 2.9 10-5 ? :confused:
 
I rounded to two significant figures and put it in scientific notation from the answer 0.000028836

Thanks for the welcome :)
 
erm … 0.000028836 is just the top line! :biggrin:
 
Woah so it is, what a mistake to make, my new answer is 500640625.
 
I agree with Tiny Tim your arithmetic is 13 orders of magnitude adrift. This is more than a rounding error.
 
Spallation said:
Woah so it is, what a mistake to make, my new answer is 500640625.

:biggrin: Woohoo! :biggrin:​

(and you were only out originally by about 1014 ! o:))
 
Indeed, how embarrasing! Thank you for the help.
 

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