Equilibrium Shift

Let a reversible gas reaction settle into equilibrium, then disturb it — add a reactant, remove product, compress or expand the vessel, or heat or cool it — and watch the concentrations shift and resettle into a new equilibrium, with a visible colour change for the nitrogen dioxide reaction.

Still frame from the Equilibrium Shift simulation
Requires Interstellar

What you can adjust

Reaction
0 – 1

Which reversible gas-phase reaction to run.

Temperature
260 – 340 K

Starting temperature. 298 K (~25 degC) is the reference temperature the equilibrium constant is quoted at.

Initial [reactant A]
0 – 1 mol/L

Starting concentration of the first reactant (NO2, or N2 for the Haber reaction).

Initial [reactant B]
0 – 1 mol/L

Starting concentration of the second reactant. Only used by the N2 + 3 H2 <=> 2 NH3 reaction (H2) — ignored for 2 NO2 <=> N2O4, which has only one reactant.

Initial [product]
0 – 1 mol/L

Starting concentration of the product (N2O4, or NH3 for the Haber reaction).

Disturbance
0 – 7

What disturbs the equilibrium partway through the run. 'Add inert gas' is the case everyone gets wrong — at constant volume it changes nothing, because it changes no reacting species' concentration.

Disturbance time
1 – 8 s

When (in seconds) the disturbance is applied. The reaction is given this long to reach its initial equilibrium first.