Chemical Reactions Simulator

What the simulator does

This tool provides two independent modules for the study of chemical reactions:

• Limiting Reagent — Given a balanced (or unbalanced) equation and the mass or mole quantities of each reactant, the simulator identifies the limiting reagent, calculates the theoretical yield of all products, and reports the excess mass remaining after the reaction is complete.
• Redox (Ion-Electron Method) — Provides a fully worked, step-by-step balance of selected oxidation-reduction reactions in acidic or basic medium using the half-reaction (ion-electron) method.

Limiting reagent — method

The simulator applies the standard five-step stoichiometric algorithm:

1. Convert all reactant masses to moles using IUPAC 2021 atomic masses.
2. Divide the moles of each reactant by its stoichiometric coefficient to obtain the molar ratio.
3. The reactant with the smallest ratio is the limiting reagent.
4. Compute the theoretical yield of each product from the limiting molar ratio.
5. Compute the excess mass remaining for each non-limiting reactant.

If the equation entered is not balanced, the simulator applies Gaussian elimination over the stoichiometric matrix and automatically balances it before proceeding.

Redox — ion-electron method

The half-reaction method balances redox equations in five stages:

1. Assign oxidation numbers to all species.
2. Identify which species is oxidised and which is reduced.
3. Write and balance the oxidation half-reaction (atoms, then charge with e⁻).
4. Write and balance the reduction half-reaction (atoms, H₂O, H⁺ or OH⁻, then e⁻).
5. Multiply each half-reaction by the LCM of electrons transferred and add them.

How to use the simulator

• Use -> as the reaction arrow (e.g., 2H2 + O2 -> 2H2O).
• Coefficients are optional; unbalanced equations are accepted and auto-balanced.
• Enter quantities in grams (g) or moles (mol) using the unit selector.
• Enable Training Mode to hide the limiting reagent and test yourself before revealing the answer.
• For Redox, use the example buttons to load a supported reaction, or type a compatible ionic equation in the input field.

Engineering assumptions & limitations

• All reactions are assumed to proceed to completion (100 % conversion).
• Molar masses are calculated from the IUPAC 2021 standard atomic weights.
• Ionic charges in formulas are ignored during molecular formula parsing (the parser skips non-alphabetic, non-digit characters).
• The automatic balancer uses exact rational arithmetic (Gauss-Jordan on the stoichiometric matrix) and requires every element present in the reactants to also appear in the products.
• The Redox module currently supports three pre-defined reactions. Free-input redox equations are matched against these; unsupported reactions are reported.
• No thermodynamic or kinetic data (enthalpy, rate constants) is modelled.

Frequently asked questions