Consider the mixture of ethanol, C2H5OH, and O2 shown in the accompanying diagram. (b) Which reactant is the limiting reactant?

Key Concepts

Limiting Reactant

The limiting reactant is the substance that is completely consumed first in a chemical reaction, thus determining the maximum amount of product that can be formed. In a reaction, if one reactant is present in a lesser amount than required by the stoichiometric ratios, it limits the extent of the reaction, leading to incomplete conversion of other reactants.

Stoichiometry

Stoichiometry is the calculation of reactants and products in chemical reactions based on the balanced chemical equation. It involves using mole ratios derived from the coefficients of the balanced equation to determine how much of each reactant is needed or how much product can be formed, which is essential for identifying the limiting reactant.

Molar Ratios

Molar ratios are the ratios of the amounts of reactants and products in a balanced chemical equation, expressed in moles. These ratios are crucial for determining how much of each reactant is required for a reaction and for identifying which reactant will be consumed first, thus establishing the limiting reactant in the process.