Haber Process Lab
Make a prediction. Change a condition. Find the compromise.
A reversible reaction, in motion
Shapes show N₂, H₂ and NH₃. Each represents a share of the gas; the display is not a literal molecule count or collision simulation.
Percent of the nitrogen atoms in this mixture that are in ammonia. For a fresh 1:3 N₂:H₂ feed, this also equals nitrogen conversion.
Start with the compromise
Try lowering the temperature: watch the equilibrium target rise while the response becomes slower.
Disturb the mixture
Temperature and total pressure stay controlled. The chamber adjusts volume as the gas amount changes.
Mixture vs equilibrium target
Illustrative model time, not real reactor seconds. Each condition change starts a new trace. The dashed line is the equilibrium target, not a reaction rate.
Yield is only part of the decision
Compare the same fresh 1:3 feed under different conditions. Lower temperature helps equilibrium yield; higher temperature helps speed. Higher pressure brings compression and equipment demands.
Speed, heating and pressure-demand indices are teaching comparisons, not measured throughput, energy bills or profit. 1× means the starting 450 °C, 200 bar, catalyst-on scenario.
| Settings | Equilibrium conversion | Response speed | Heating demand | Pressure demand | Actions |
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Separate the ammonia. Reuse the feed.
Simplified process diagram. Real plants also manage heat recovery, impurities and purge streams. The Experiment tab models a controlled batch, not this entire flow loop.
The science behind this model
N₂(g) + 3H₂(g) ⇌ 2NH₃(g), ΔH ≈ −92 kJ per reaction as written. The forward reaction is exothermic. An iron catalyst provides a lower-activation-energy pathway for both directions; it changes the speed, not the equilibrium position.
The equilibrium calculation uses ideal-gas partial pressures at controlled temperature and total pressure, with a 1 bar standard state. It uses a fixed-enthalpy van ’t Hoff approximation and an illustrative reference K = 1.01 × 10⁻⁵ at 450 °C. Real high-pressure gases are nonideal: these percentages are learning-model outputs, not factory predictions.
Response speed is an illustrative temperature-dependent relaxation towards equilibrium. It is not a measured kinetic law. At equilibrium forward and reverse reactions still occur; equal rates do not mean equal gas amounts. Particle motion is illustrative.
The starting 450 °C and 200 bar illustrate the familiar classroom compromise. Industrial conditions vary with catalyst and plant design. The notebook compares ideal equilibrium conversion for fresh feed, not actual single-pass throughput or whole-plant yield.
Sources: OpenStax: shifting equilibria · University of York: ammonia manufacture. Continue with reversible reactions and equilibrium.