Thermodynamics - Calculating K of reaction

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SUMMARY

The discussion centers on calculating the equilibrium constant (K) for the reaction 2N2O4 (g) + O2 (g) → 2N2O5 (g) at 298K. The correct approach involves using the Gibbs free energy change (ΔG°) of 34.4 kJ/mol and the equation K = e^(-ΔG°/RT). A common mistake identified was using the gas constant R in kJ instead of Joules, which led to an incorrect calculation of K as 0.98495. The correct calculation requires converting ΔG° to Joules for accurate results.

PREREQUISITES
  • Understanding of Gibbs free energy and its relation to equilibrium constants
  • Familiarity with the ideal gas law and thermodynamic equations
  • Knowledge of unit conversions, specifically between kJ and Joules
  • Proficiency in using exponential functions in calculations
NEXT STEPS
  • Review the principles of thermodynamics, focusing on Gibbs free energy and equilibrium
  • Practice unit conversion techniques, especially for thermodynamic constants
  • Explore the implications of temperature on reaction equilibria
  • Learn about the significance of the gas constant (R) in thermodynamic equations
USEFUL FOR

Chemistry students, educators, and professionals involved in thermodynamics and chemical reaction analysis will benefit from this discussion.

Bill Nye Tho
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Homework Statement



Establish K at 298K for the reaction:

2N2O4 (g) + O2 (g) → 2N2O5 (g)

Homework Equations



ΔG° = -RTlnK

The Attempt at a Solution



I've established that ΔG° = 34.4 kJ/mol (Correct) but for some reason when I solve for:

K = eΔG°/-RT

K = e34.5/(-(8.314)(298)) = .98495

I get the wrong answer.
 
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Ah, silly me... The units for my gas constant are in Joules not kJoules.

Got it.
 

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