Quantitative Analysis of Iron Sulfide Formation: The Impact of Reactant Molar Ratios

Iron sulfide, also known as iron(II) sulfide, is a compound commonly formed through the chemical reaction between iron and sulfur. Knowing the precise amount of iron sulfide that can be produced from a given amount of reactants is crucial for various industrial and chemical applications. This article will walk you through the process of determining the amount of iron sulfide produced when 56 grams of iron and 40 grams of sulfur are mixed and heated under controlled conditions.

Determining the Limiting Reactant

To understand how much iron sulfide (FeS) will be formed, we must first determine the limiting reactant. The reaction between iron (Fe) and sulfur (S) to form iron sulfide can be represented by the following balanced chemical equation:

Fe     S  →  FeS

The molar masses of the reactants are:

Iron (Fe): 55.85 g/mol Sulfur (S): 32.07 g/mol

With these molar masses, we can calculate the number of moles of each reactant:

Iron: 56 g ÷ 55.85 g/mol 1 mol Sulfur: 40 g ÷ 32.07 g/mol 1.25 mol

The mole ratio of iron to sulfur in the balanced equation is 1:1. Therefore, the theoretical reaction requires equal moles of iron and sulfur. Given that we have 1 mol of iron and 1.25 mol of sulfur, iron is the limiting reactant because it will be completely consumed before sulfur. The reaction will proceed until all the iron is used up.

Calculating the Amount of Iron Sulfide Produced

Since iron is the limiting reactant, the amount of iron sulfide formed will be equal to the amount of iron available:

Moles of FeS formed 1 mol (same as moles of Fe)

To find the mass of iron sulfide (FeS) produced, we use its molar mass, which is:

Molar mass of FeS 56 g/mol (Fe) 32 g/mol (S) 88 g/mol

Therefore, the mass of FeS formed can be calculated as:

Mass of FeS  1 mol × 88 g/mol  88 g

This calculation shows that if 56 grams of iron and 40 grams of sulfur are mixed together and heated, 88 grams of iron sulfide will be formed under ideal conditions.

Conclusion

The quantitative analysis of iron sulfide formation is a fundamental concept in stoichiometry. By understanding the limiting reactant and the mole ratios, we can predict and control the amount of product formed in a chemical reaction. This knowledge is invaluable in a variety of fields, including chemical engineering, material science, and environmental applications.

References

For a deeper understanding of this topic, you may refer to the following resources:

Stoichiometry Examples Limiting Reactant from LibreTexts