Here's how to determine the limiting reagent:

1. Write a balanced chemical equation: This shows the stoichiometric ratios of reactants and products.

2. Calculate the moles of each reactant: Use the given masses and molar masses.

3. Determine the mole ratio of reactants: Compare the calculated moles of each reactant to the stoichiometric coefficients in the balanced equation.

4. Identify the limiting reagent: The reactant with the smallest mole ratio relative to its coefficient in the balanced equation is the limiting reagent.

Example:

Consider the reaction:

2 H₂ (g) + O₂ (g) → 2 H₂O (l)

Let's say we have:

* 4 grams of H₂

* 16 grams of O₂

1. Balanced equation: Already given.

2. Moles of reactants:

* H₂: 4 g / 2 g/mol = 2 moles

* O₂: 16 g / 32 g/mol = 0.5 moles

3. Mole ratio:

* H₂: 2 moles / 2 = 1

* O₂: 0.5 moles / 1 = 0.5

4. Limiting reagent: O₂ has the smaller mole ratio (0.5) compared to its coefficient in the balanced equation (1). Therefore, O₂ is the limiting reagent.

Important note: The limiting reagent determines the theoretical yield of the product, which is the maximum amount of product that can be formed.