9.35g sample of oleum is added to 1 ltr of 1.6 M naoh solution density 1g/ml. If concentration of H+ ions in remaining solution is .4M , the percentage labelling of oleum is

To determine the percentage labeling of oleum in this scenario, we need to analyze the chemical reaction that occurs when oleum is mixed with sodium hydroxide (NaOH). Oleum is a solution of sulfur trioxide (SO3) in sulfuric acid (H2SO4), and it can release H+ ions when it reacts with NaOH. Let's break down the problem step by step.

Understanding the Reaction

When oleum is added to NaOH, the sulfur trioxide reacts with the hydroxide ions (OH-) from the NaOH to form sulfate ions (SO4^2-) and water. The reaction can be simplified as follows:

• SO3 + 2 NaOH → Na2SO4 + H2O

In this reaction, each mole of SO3 will produce two moles of NaOH. Therefore, we need to find out how many moles of H+ ions are present in the solution after the reaction to determine how much oleum was present initially.

Calculating Moles of H+ Ions

We know that the concentration of H+ ions in the remaining solution is 0.4 M. Since the total volume of the solution is 1 liter, we can calculate the number of moles of H+ ions:

• Moles of H+ = Concentration × Volume = 0.4 mol/L × 1 L = 0.4 moles

Relating Moles of H+ to Oleum

In the reaction, each mole of SO3 produces 2 moles of H+ ions. Therefore, to find the moles of SO3 that reacted, we can use the following relationship:

• Moles of SO3 = Moles of H+ / 2 = 0.4 moles / 2 = 0.2 moles

Calculating Mass of Oleum

Next, we need to find the mass of SO3 that corresponds to 0.2 moles. The molar mass of SO3 is approximately 80 g/mol. Thus, the mass of SO3 is:

• Mass of SO3 = Moles × Molar Mass = 0.2 moles × 80 g/mol = 16 g

Finding the Percentage Labeling of Oleum

Now, we can find the percentage of oleum in the original 9.35 g sample. The percentage labeling can be calculated using the formula:

• Percentage of Oleum = (Mass of SO3 / Mass of Oleum Sample) × 100

Substituting the values we have:

• Percentage of Oleum = (16 g / 9.35 g) × 100 ≈ 171.5%

This result indicates that the calculation suggests an inconsistency, as a percentage over 100% is not physically meaningful. This discrepancy may arise from the assumption that all H+ ions are derived solely from the oleum, or it could indicate that the oleum sample contains additional components or impurities that were not accounted for. Therefore, further investigation into the composition of the oleum sample might be necessary to clarify this result.

Final Thoughts

In summary, while we calculated a percentage labeling of oleum based on the reaction with NaOH, the outcome suggests that there may be more to the composition of the oleum sample than initially considered. Understanding the chemistry involved and the assumptions made is crucial for accurate analysis in such scenarios.