Equal rates, not equal amounts.
A closed reaction keeps working in both directions. Change its temperature or starting mixture, then watch the two rates converge.
Forward · A → B
[A] = 0 · kf = 0 /sReverse · B → A
[B] = 0 · kr = 0 /sEquilibrium B/A = 0 · elapsed 0 s
Reduced motion: use Step to advance. Concentrations are relative units, with [A] + [B] = 1. Sixty rounded markers represent the mixture; their turnover is schematic, not molecular trajectories. Both dials share a 0–1.4 /s scale.
Speed is not the final mixture.
Heating speeds up both directions. Here A → B is chosen to be exothermic, so heating lowers kf/kr and favors A. At equilibrium both nonzero rates are equal, even when the amounts are not.
An honest teaching model.
Ideal first-order conversion in a closed, fixed-volume system: no catalyst, side reaction or volume change. Temperature is an illustrative 0–100 scale, not kelvin or real chemical data. Exact exponential stepping preserves nonnegative concentrations.
With θ = temperature/100: kf = 0.35 e^(1.1θ), kr = 0.10 e^(2.5θ) /s.