9827

Chemical Equilibrium in the Haber Process

The number of moles at equilibrium is calculated for the Haber process, the reversible, exothermic reaction that synthesizes ammonia ) from hydrogen () and nitrogen (). The reaction is typically carried out at around 200 bar and 675–725 K. You can vary the pressure and temperature in this Demonstration. Gases are assumed to behave ideally, although realistically at the high pressures used in this reaction, there is significant deviation from ideal behavior. Four moles of reactants form two moles of product, so raising the pressure shifts equilibrium toward products. Initially, the system is filled with one mole of ammonia and allowed to reach equilibrium. At equilibrium, you can add additional nitrogen, hydrogen, and/or ammonia at constant pressure, and the effect on the equilibrium is observed. Le Chatelier's principle predicts that when nitrogen or hydrogen are added, the reaction goes to the right, whereas when ammonia is added, the reaction shifts to the left. However, when the nitrogen/hydrogen ratio is sufficiently high, adding nitrogen shifts reaction to the left (i.e. adding nitrogen decreases the amount of ammonia and increases the amount of hydrogen), contrary to what Le Chatelier's principle predicts. This happens because adding nitrogen decreases the mole fraction of hydrogen, and because the hydrogen mole fraction is cubed in the equilibrium expression, ammonia reacts to increase the number of moles of hydrogen and nitrogen.

SNAPSHOTS

  • [Snapshot]
  • [Snapshot]
  • [Snapshot]

DETAILS

The reaction is .
Constants
, heat of reaction (enthalpy change for reaction)
, entropy change of reaction
, ideal gas constant
Equilibrium Rate Constant
= temperature (K)
, Gibbs free energy
, equilibrium constant (dimensionless)
Equilibrium Composition
= extent of reaction
= initial moles of
= initial moles of
= initial moles of
, total moles
, equilibrium concentration of
, equilibrium concentration of
, equilibrium concentration of
, mole fraction of
, mole fraction of
, mole fraction of
= , equilibrium rate constant (pressure must be in bars)
, reaction quotient
= possible values for extent of reaction
In the code, "eqx" is the correct value for extent of reaction.
    • Share:

Embed Interactive Demonstration New!

Just copy and paste this snippet of JavaScript code into your website or blog to put the live Demonstration on your site. More details »

Files require Wolfram CDF Player or Mathematica.









 
RELATED RESOURCES
Mathematica »
The #1 tool for creating Demonstrations
and anything technical.
Wolfram|Alpha »
Explore anything with the first
computational knowledge engine.
MathWorld »
The web's most extensive
mathematics resource.
Course Assistant Apps »
An app for every course—
right in the palm of your hand.
Wolfram Blog »
Read our views on math,
science, and technology.
Computable Document Format »
The format that makes Demonstrations
(and any information) easy to share and
interact with.
STEM Initiative »
Programs & resources for
educators, schools & students.
Computerbasedmath.org »
Join the initiative for modernizing
math education.
Step-by-step Solutions »
Walk through homework problems one step at a time, with hints to help along the way.
Wolfram Problem Generator »
Unlimited random practice problems and answers with built-in Step-by-step solutions. Practice online or make a printable study sheet.
Wolfram Language »
Knowledge-based programming for everyone.
Powered by Wolfram Mathematica © 2014 Wolfram Demonstrations Project & Contributors  |  Terms of Use  |  Privacy Policy  |  RSS Give us your feedback
Note: To run this Demonstration you need Mathematica 7+ or the free Mathematica Player 7EX
Download or upgrade to Mathematica Player 7EX
I already have Mathematica Player or Mathematica 7+