What is Stoichiometry?
Stoichiometry is the quantitative study of reactants and products in chemical reactions. It relies on the law of conservation of mass and the concept of the mole to predict how much of each substance is needed or produced. A balanced chemical equation provides the mole ratios; from these ratios you can convert between any pair of substances in the reaction.
How Mole Ratios Work
In the equation 2H2 + O2 -> 2H2O, the coefficients tell us that 2 moles of hydrogen gas react with 1 mole of oxygen gas to produce 2 moles of water. These ratios are the key to all stoichiometric calculations; once you know the moles of any one substance, you can find the moles of every other substance by simple proportion.
Unit Conversions
Stoichiometry problems often require converting between different measurement units. Grams are converted to moles using molar mass (grams per mole). Liters of gas at STP are converted using the molar volume of 22.4 L/mol. Particle counts use Avogadro's number (6.022 x 10^23 particles per mole). This calculator handles all four conversions automatically.
Limiting Reagent Analysis
When reactant amounts are not in the exact stoichiometric ratio, one reactant will be completely consumed before the others. This is the limiting reagent; it determines the theoretical yield. The excess reagent is left over after the reaction completes. Identifying the limiting reagent is essential for lab work and industrial processes.
