Determining Limiting and Excess Reactants in the Hydrogen and Oxygen Reaction

Understanding the concepts of limiting and excess reactants is essential for chemical reactions. This article explores a specific reaction between hydrogen gas (H2) and oxygen gas (O2), focusing on identifying the limiting and excess reactants based on given quantities.

Stoichiometric Equation and Balanced Reaction

The balanced chemical equation for the reaction between hydrogen and oxygen to produce water is:

2H2 O2 → 2H2O

This equation indicates that 2 moles of hydrogen gas react with 1 mole of oxygen gas to produce 2 moles of water. Let's consider a scenario where 10 moles of hydrogen gas (H2) react with 7 moles of oxygen gas (O2).

Analyzing the Given Quantities

Step 1: Identify the Required Quantities

Based on the balanced equation, the required ratio of hydrogen to oxygen is 2:1. This means for every 2 moles of H2, 1 mole of O2 is needed to fully react.

Step 2: Calculate the Required Moles of Oxygen

Given 10 moles of H2, the required moles of O2 can be calculated using the stoichiometric ratio:

10 moles H2 × (1 mole O2 / 2 moles H2) 5 moles O2

Hence, 5 moles of O2 are required to react completely with 10 moles of H2.

Step 3: Identify the Limiting and Excess Reactants

Since only 7 moles of O2 are provided, but only 5 moles are needed, the oxygen is in excess. Conversely, the hydrogen (10 moles) is insufficient to react with all the oxygen. Therefore, hydrogen is the limiting reactant, and oxygen is the excess reactant.

Conclusion

Based on the given quantities:- Hydrogen (H2) - 10 moles (limiting reactant)- Oxygen (O2) - 7 moles (excess reactant)

Understanding the Production of Water

From the balanced equation, each mole of H2 produces 1 mole of H2O. Therefore:

10 moles of H2 → 10 moles of H2O

This confirms that 10 moles of H2 can produce 10 moles of H2O, provided there is enough O2 to react with it.

Further Analysis

The coefficients in the balanced chemical reaction equation (2 H2 O2 → 2 H2O) are proportional to the moles. Starting with the balanced reaction equation:

2H2 O2 → 2H2O

If we have 10 moles of H2, the ratio tells us that 10 moles of H2 will produce 10 moles of H2O. Similarly, 2 moles of H2 produce 2 moles of H2O, hence the relationship is consistent.