Determining the Limiting Reactant in the Reaction of Carbon Monoxide and Hydrogen

In this article, we will explore the process of determining the limiting reactant in the reaction between carbon monoxide (CO) and hydrogen (H2). This is a fundamental concept in chemistry that is crucial for understanding the efficiency of reactions and the production of desired products like methane (CH4) and water (H2O).

Reaction Overview

The given reaction is an incomplete combustion process:

CO 3H2 → CH4 H2O

This reaction demonstrates the formation of methane and water from carbon monoxide and hydrogen. Understanding the limiting reactant is essential for optimizing the efficiency of such reactions, especially in industrial and laboratory settings.

Step-by-Step Calculation

Step 1: Calculate the Moles of Reactants

To determine the limiting reactant, we first need to calculate the moles of the reactants.

Carbon Monoxide (CO): Molar mass of CO: 12.01 (C) 16.00 (O) 28.01 g/mol Moles of CO: 15 g / 28.01 g/mol 0.535 moles Hydrogen (H2): Molar mass of H2: 2.02 g/mol Moles of H2: 8 g / 2.02 g/mol 3.96 moles

Step 2: Determine the Stoichiometric Requirements

From the balanced chemical equation, we see that 1 mole of CO reacts with 3 moles of H2.

Step 3: Calculate the Required Moles of H2 for the Available Moles of CO

To find out how much H2 is needed to react with the given amount of CO:

Required moles of H2: 0.535 moles CO × 3 moles H2/mol CO 1.605 moles H2

Step 4: Compare Available Moles of H2 with Required Moles

Reactant Available Moles Required Moles Conclusion CO 0.535 moles 1.605 moles Not limiting H2 3.96 moles 1.605 moles Excess reactant

Since we have more H2 available than required, CO is the limiting reactant.

Step 5: Determine the Limiting Reactant

Since CO requires 1.605 moles of H2 to completely react, and we have enough H2 to react with CO, CO is the limiting reactant. This means CO will be completely consumed in the reaction, limiting the amount of products (CH4 and H2O) that can be formed.

Conclusion

The limiting reactant in the reaction between 15 grams of CO and 8 grams of H2 is CO. This conclusion is based on the stoichiometric ratio and the amount of reactants available. Identifying the limiting reactant is crucial for determining the yield and efficiency of chemical reactions.

Key Concepts

Limiting Reactant: The reactant that is completely consumed in a chemical reaction and limits the amount of product formed. Stoichiometry: The quantitative relationships among reactants and products in a chemical reaction. Products vs. Reactants: Reactants are the substances that undergo chemical change in a reaction, while products are the substances formed from the reaction.

FAQs

What is a limiting reactant? The limiting reactant is the reactant that is entirely used up during a chemical reaction, and it determines the amount of product formed. How do you calculate the limiting reactant? First, calculate the moles of each reactant. Then, use the stoichiometric ratio to determine how much of each reactant is required. The reactant that provides less than its required amount is the limiting reactant. What happens after the limiting reactant is used up? Once the limiting reactant is used up, the reaction stops, and any remaining reactants remain unreacted.

Key Terms

limiting reactant, CO and H2 reaction, stoichiometry, methane formation