Calculation of Aluminum Sulfate Production from Aluminum and Sulfuric Acid

Understanding the balanced chemical equation and applying stoichiometry to calculate the production of aluminum sulfate from aluminum and sulfuric acid is crucial in chemistry and industrial processes. In this article, we will walk through a detailed example of calculating the number of moles of aluminum sulfate (chemical formula: Al2(SO4)3) formed when 20.0 grams of aluminum is exposed to a sulfuric acid solution containing 115 grams of sulfuric acid (H2SO4). We will use two methods for this calculation, ensuring a comprehensive understanding of the concept.

Relevant Chemical Reaction and Molar Mass Calculation

The balanced chemical equation for the reaction between aluminum and sulfuric acid is as follows:

2Al 3H2SO4 → Al2(SO4)3 3H2

Method 1: Using Mole Ratios

First, let's calculate the initial moles of aluminum and sulfuric acid:

Molar mass of Al 27.0 g/mol

Molar mass of H2SO4 1.0 x 2 32.1 16.0 x 4 98.1 g/mol

Using the molar mass, we can find the moles of each reactant:

Initial moles of Al 20.0 g / 27.0 g/mol 0.7407 mol

Initial moles of H2SO4 115 g / 98.1 g/mol 1.172 mol

Based on the given equation, the mole ratio in the reaction is 2:3 for Al to H2SO4. Since the initial moles of Al : H2SO4 0.7407 : 1.172 2 : 3.165, sulfuric acid is in excess and aluminum is the limiting reactant. Therefore, we can calculate the moles of Al2(SO4)3 produced as follows:

Moles of Al2(SO4)3 produced 0.7407 mol × (1/2) 0.370 mol

Method 2: Complete Reaction Assumption

Another method involves assuming complete reaction of each reactant and comparing the yields:

Assuming complete reaction of aluminum:

20.0 g Al × (1 mol Al / 27.0 g Al) × [1 mol Al2(SO4)3 / 2 mol Al] 0.370 mol Al2(SO4)3

Assuming complete reaction of sulfuric acid:

115 g H2SO4 × (1 mol H2SO4 / 98.1 g H2SO4) × [1 mol Al2(SO4)3 / 3 mol H2SO4] 0.391 mol Al2(SO4)3

Here, the limiting reactant gives the lowest yield. Hence, aluminum is the limiting reactant and the moles of Al2(SO4)3 produced are 0.370 mol.

Conclusion and Key Takeaways

In this article, we have demonstrated two methods to calculate the moles of aluminum sulfate produced from aluminum and sulfuric acid. The first method uses direct mole ratios, while the second method involves assuming the complete reaction of each reactant and comparing the yields. It is important to identify the limiting reactant in order to determine the maximum amount of product that can be formed.

Understanding these calculations is essential for various industrial processes, such as making fertilizers, detergents, and metal treatments. By mastering the concept of limiting reactants and stoichiometry, you can optimize chemical reactions and improve efficiency in industrial settings.