Why Magnesium is Identified as the Limiting Reactant in Our Experimental Analysis

Why is Magnesium the Limiting Reactant in This Experiment?

In any chemical reaction, the limiting reactant is the substance that is completely consumed, thereby determining the maximum amount of product that can be formed. Identifying the limiting reactant is crucial in understanding the efficiency and yield of a reaction. This article aims to explore why magnesium was determined to be the limiting reactant in a particular experiment.

The Experiment and Its Purpose

The experiment in question involved the reaction between magnesium and hydrochloric acid to produce hydrogen gas and magnesium chloride. The primary objective was to investigate the stoichiometry of the reaction and to determine the limiting reactant. By doing so, we could calculate the theoretical yield of the hydrogen gas and compare it to the actual yield obtained.

Stoichiometry and Balanced Chemical Equation

To understand why magnesium was the limiting reactant, we must first examine the balanced chemical equation for the reaction:

Mg (s) + 2HCl (aq) → MgCl2 (aq) + H2 (g)

From the equation, we can see that one mole of magnesium reacts with two moles of hydrochloric acid to produce one mole of magnesium chloride and one mole of hydrogen gas. This stoichiometric ratio is essential in determining the limiting reactant.

Quantifying Reactants and Their Moles

In the experiment, the amount of magnesium and hydrochloric acid used were measured in grams. To determine the moles of each reactant, we divided the mass by their respective molar masses:

– Moles of magnesium = mass of magnesium / molar mass of magnesium
– Moles of hydrochloric acid = mass of hydrochloric acid / molar mass of hydrochloric acid

After calculating the moles of both reactants, we found that the experiment used more hydrochloric acid than magnesium. However, this does not necessarily mean that hydrochloric acid is the limiting reactant.

Calculating Moles of Reactants Needed for Complete Reaction

To determine the limiting reactant, we must compare the moles of each reactant to the stoichiometric ratio. Since one mole of magnesium reacts with two moles of hydrochloric acid, we can calculate the moles of hydrochloric acid needed for complete reaction with the available magnesium:

– Moles of hydrochloric acid needed = moles of magnesium × (2 moles of HCl / 1 mole of Mg)

If the moles of hydrochloric acid needed are less than the actual moles of hydrochloric acid used, then magnesium is the limiting reactant. In this case, the moles of hydrochloric acid needed were indeed less than the moles of hydrochloric acid used, confirming that magnesium is the limiting reactant.

Implications of the Limiting Reactant

Identifying magnesium as the limiting reactant in this experiment has several implications. First, it means that the maximum amount of hydrogen gas that could be produced is limited by the amount of magnesium available. Second, it allows us to calculate the theoretical yield of the hydrogen gas, which can be compared to the actual yield to assess the efficiency of the reaction. Lastly, it provides insight into the stoichiometry of the reaction and the role of each reactant in the overall process.

In conclusion, magnesium was identified as the limiting reactant in this experiment due to its lower moles compared to hydrochloric acid and the stoichiometric ratio of the reaction. This finding has important implications for understanding the reaction’s efficiency and yield, as well as the role of each reactant in the overall process.