Try neighboring patches of hydrogen and oxygen at 900 K for combustion. Compare the same mixture at room temperature. Put hot water beside ice to watch heat transfer. Overlap acid and base solutions for neutralization, or copper sulfate and base for a blue precipitate. Iron and magnesium strokes form connected solid chunks. They conduct heat, lose their rigid connections as they melt, and react at exposed surfaces. Hot carbon and carbon dioxide can form carbon monoxide while absorbing heat. Prepare everything before Play: the running chamber is sealed.

Pause and select Inspect to examine a particle and its metal connections without editing. Your first edit establishes a new setup on the next Play. Reset restores the last sealed setup, including its random seed and metal connections. Ice and steam are water at different preparation temperatures; selecting either adjusts the temperature control. No experiment data leaves your browser.

This is a mesoscopic classroom model, not a laboratory predictor. The energy ledger uses joules, metres, seconds, moles and kelvin. It includes formation-energy references, thermal and latent energy, resolved kinetic energy, gravity and trapped radiation. Water has reversible latent-heat plateaus at nominal 1-bar temperatures; pressure-dependent boiling, solvent activity, ion solvation, detailed reaction mechanisms, high-temperature dissociation and metal vaporization and most other phase changes are omitted. Iron and magnesium include melting and latent heat; their connected shape model is a coarse metallic-cohesion abstraction, with finite surface/binding energy and locally accounted constraint work. It does not simulate electrons, crystal lattices, calibrated stress/strain, or alloys. Heat capacities are piecewise constant. Parcel size, collision cross sections, gas relaxation and effective reaction rates are scaled for visibility; the pressure display measures resolved wall impacts, not a calibrated gas-law prediction. The chamber has a 2D cross section and a defined 1 mm model depth. No full CFD or molecular accuracy is claimed.

Reaction probability follows 1 − exp(−k Δt), with temperature-dependent Arrhenius rates and local reactant availability. Listed activation barriers and effective prefactors are teaching parameters, not measured kinetics. Precipitation is a local kinetic approximation rather than a complete solubility-equilibrium solver. Brightness exaggerates actual heat release; visual effects never add physical energy. Use this virtual model for exploration, not instructions for real mixing.

Reference basis: NIST thermochemistry · OpenStax phase changes. Detailed constants, limitations and measured test results accompany the source.