Runs Out

which tray empties first? bet, then watch.

bet on which reactant runs out first, then watch a model kit run the balanced equation turn by turn until one tray cannot pay: the limiting reagent

A reaction uses its reactants in the ratio of the equation, so the one that runs out first is not simply the one you have less of. Divide each amount (in moles) by its coefficient: the smaller answer is the limiting reagent. That number of turns sets the product, and the other reactant is left over by what it did not use. With masses, turn grams into moles first.

Concepts: chemistry, ratio.

An interactive you play with one thumb, on Wundr.