Finding the Limiting Reagent

This limiting reagent calculator converts each reactant's mass to moles using its molar mass, then divides by its stoichiometric coefficient. The smaller quotient identifies the limiting reagent — the substance that runs out first — while the other reactant is in excess.

Theoretical Yield

The limiting reagent fixes the maximum product: its usable moles times the product coefficient gives product moles, and multiplying by the product's molar mass gives the theoretical yield in grams. Real processes recover less, but this is the ceiling.

Excess Reagent

Subtracting the moles actually consumed from the moles available tells you how much of the other reactant survives. The excess mass is reported in grams so you can see exactly what was wasted — and what could be recovered.