Identifying the Limiting Reactant in a Chemical Reaction Involving CO and H?

When 15 grams of carbon monoxide (CO) and 8 grams of hydrogen (H?) are reacted, understanding the limiting reactant is crucial for predicting the outcome of the reaction. This article will walk you through the process of determining the limiting reactant, the balance chemical equation, and the stoichiometric calculations involved.

Step-by-Step Guide to Determining the Limiting Reactant

Step 1: Calculate Moles of Reactants

First, we need to write the balanced chemical equation for the reaction:

2CO 2H2 → 2C 2H2O

Step 2: Calculate Moles of CO and H?

Molar Mass of CO:

- C: 12.01 g/mol
- O: 16.00 g/mol
- Molar Mass of CO 12.01 16.00 28.01 g/mol

Molar Mass of H?:

- H: 1.01 g/mol
- Molar Mass of H? 2 × 1.01 2.02 g/mol

Calculate moles of CO:

n(CO) 15 g / 28.01 g/mol ≈ 0.535 moles

Calculate moles of H?:

n(H?) 8 g / 2.02 g/mol ≈ 3.96 moles

Determine the Stoichiometry

From the balanced equation, we see that the stoichiometric ratio of CO to H? is 1:1. Therefore, we need equal moles of CO and H? to completely react.

Compare Available Moles

Moles of CO available: 0.535 moles

Moles of H? available: 3.96 moles

Identify the Limiting Reactant

Since the reaction requires 1 mole of CO for every 1 mole of H?, we can compare the moles available:

For the available 0.535 moles of CO, we would need 0.535 moles of H?.

We have 3.96 moles of H? available, which is more than enough.

Conclusion

Therefore, CO is the limiting reactant because we do not have enough CO to react with all the available H?.

Additional Insight: Incomplete Combustion and Products Formation

This is an incomplete combustion reaction that yields CO2 and H?O and heat:

2CO 2H? → CH? H?O

To find the limiting reagent:

Mass of CO 15 g

Molar mass of CO 28 g/mol Moles of CO 15 g / 28 g/mol 0.535 moles Dividing moles by its coefficient ratio: 0.535 / 2 0.2675

Mass of H? 8 g

Molar mass of H? 2 g/mol Moles of H? 8 g / 2 g/mol 4 moles Dividing moles by its coefficient ratio: 4 / 2 2

Based on the stoichiometric ratio, CO is the limiting reagent, and H? is the excess reactant that will not fully react. This information is essential for understanding the products formed in the reaction.