Calculation of O2 Volume from H2O2 Decomposition at STP

Understanding the stoichiometry and behavior of gases under standard temperature and pressure (STP) is crucial for scientific and industrial applications. This article provides a detailed explanation and a step-by-step guide on how to calculate the volume of oxygen (O2) produced from the decomposition of hydrogen peroxide (H2O2) at STP conditions.

Stoichiometric Balanced Equation

The decomposition of hydrogen peroxide into water and oxygen can be represented by the following balanced chemical equation:

2H2O2(aq) → 2H2O(l) O2(g)

This equation indicates that 2 moles of H2O2 decompose to produce 1 mole of O2. This stoichiometric relationship forms the basis for our calculations.

Calculation Steps

To calculate the volume of O2 released, we need to follow several steps:

Step 1: Write the balanced equation

2H2O2(aq) → 2H2O(l) O2(g)

Step 2: Convert the given amount to moles

First, determine the number of moles of H2O2 in the given solution.

Number of moles of H2O2 Molarity × Volume (in liters)

Given: 2.0 M H2O2 and 250 mL solution.

Number of moles 2.0 mol/L × 250/1000 L 0.50 mol

Step 3: Multiply by the mole ratio

According to the balanced equation, the mole ratio of H2O2 to O2 is 2:1. Therefore, the number of moles of O2 produced can be calculated as follows:

Number of moles of O2 0.50 mol × (1/2) 0.25 mol

Step 4: Multiply by 22.4 liters/mole

At STP, one mole of any gas occupies 22.4 liters of volume. Therefore, the volume of O2 released can be calculated as follows:

Volume of O2 at STP 0.25 mol × 22.4 L/mol 5.6 L

Another way to express the calculation is:

2.0 mol H2O2 / 1 L H2O2 × 250/1000 L H2O2 × 1 mol O2 / 2 mol H2O2 × 22.4 L O2 at STP / 1 mol O2 5.6 L O2 at STP

Conclusion

The calculation above provides a straightforward method for determining the volume of oxygen produced from the decomposition of a given volume of hydrogen peroxide at STP. This understanding is not only pivotal for the academic study of chemistry but also has practical applications in industries and laboratories where gaseous reactions are studied.