The limiting reactant in a chemical reaction is one that

General
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the limiting reactant in a chemical reaction is one that

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The limiting reactant in a chemical reaction is one that

Answer:
In a chemical reaction, the limiting reactant (or limiting reagent) is the substance that is completely consumed first, thereby determining the amount of product that can be formed. This reactant limits the extent of the reaction because the reaction cannot proceed further once this reactant is exhausted. Here’s a step-by-step explanation to understand this better:

Solution By Steps:

  1. Understanding Reactants and Products:

    • A chemical reaction involves reactants transforming into products. For example, consider the reaction:

      aA + bB \rightarrow cC + dD

    Here, A and B are reactants, and C and D are products.

  2. Mole Ratios:

    • The coefficients a, b, c, and d represent the molar ratios of the reactants and products.

  3. Determining the Limiting Reactant:

    • To determine which reactant is the limiting one, follow these steps:

      1. Calculate the Moles of Each Reactant:

        • Convert the mass of each reactant to moles using their respective molar masses.

          \text{Number of moles} = \frac{\text{Given mass}}{\text{Molar mass}}

      2. Calculate the Theoretical Yield of Product for Each Reactant:

        • Using stoichiometry, calculate how much product can be formed from the given moles of each reactant.

          \text{From reactant } A: \quad \text{Moles of } C = \frac{\text{Moles of } A}{a} \times c
          \text{From reactant } B: \quad \text{Moles of } C = \frac{\text{Moles of } B}{b} \times c

      3. Identify the Limiting Reactant:

        • The reactant that produces the lesser amount of product is the limiting reactant. Once it is used up, no more product can be formed.

Practical Example:

Consider a reaction where 10 grams of hydrogen (H₂) reacts with 50 grams of oxygen (O₂) to form water (H₂O):

2H_2 + O_2 \rightarrow 2H_2O

  1. Convert grams to moles:

    • Molar mass of H₂ = 2.02 g/mol

    • Molar mass of O₂ = 32.00 g/mol

      \text{Moles of } H_2 = \frac{10 \, \text{grams}}{2.02 \, \text{g/mol}} \approx 4.95 \, \text{moles}
      \text{Moles of } O_2 = \frac{50 \, \text{grams}}{32.00 \, \text{g/mol}} \approx 1.56 \, \text{moles}

  2. Calculate theoretical yield:

    • For H₂:

      \text{Moles of } H_2O = \frac{4.95 \, \text{moles H}_2}{2} \times 2 = 4.95 \, \text{moles H}_2O

    • For O₂:

      \text{Moles of } H_2O = \frac{1.56 \, \text{moles O}_2}{1} \times 2 = 3.12 \, \text{moles H}_2O

  3. Determine the limiting reactant:

    • Since the amount of H₂O produced by O₂ (3.12 moles) is less than that produced by H₂ (4.95 moles), O₂ is the limiting reactant.

Final Answer:

The limiting reactant in a chemical reaction is the reactant that is completely consumed first, thus limiting the amount of product formed and determining when the reaction stops. In the example given, oxygen (O₂) is the limiting reactant.