Calculation of Moles of Magnesium

Oct 13, 2025 by wbrum.org 7 views

Introduction

In this article, we will discuss the balanced chemical equation for the reaction of magnesium with excess dilute hydrochloric acid at room temperature (RTP) and hydrogen gas given off was collected. The reaction between magnesium and hydrochloric acid is a classic example of a single displacement reaction, where magnesium displaces hydrogen from hydrochloric acid to form magnesium chloride and hydrogen gas.

Chemical Equation

The unbalanced chemical equation for the reaction is:

Mg + HCl → MgCl2 + H2

To balance the chemical equation, we need to ensure that the number of atoms of each element is the same on both the reactant and product sides. The balanced chemical equation for the reaction is:

2Mg + 2HCl → 2MgCl2 + H2

Explanation

In the balanced chemical equation, 2 moles of magnesium react with 2 moles of hydrochloric acid to produce 2 moles of magnesium chloride and 1 mole of hydrogen gas. The reaction is a single displacement reaction, where magnesium displaces hydrogen from hydrochloric acid to form magnesium chloride and hydrogen gas.

Calculation of Moles of Magnesium

To calculate the number of moles of magnesium, we need to know the molar mass of magnesium. The molar mass of magnesium is 24.305 g/mol. We are given that 0.48 g of magnesium was reacted with excess dilute hydrochloric acid.

Number of moles of magnesium = mass of magnesium / molar mass of magnesium = 0.48 g / 24.305 g/mol = 0.0198 mol

Calculation of Theoretical Yield of Hydrogen Gas

To calculate the theoretical yield of hydrogen gas, we need to know the number of moles of hydrogen gas produced. From the balanced chemical equation, we can see that 2 moles of magnesium produce 1 mole of hydrogen gas.

Number of moles of hydrogen gas = number of moles of magnesium / 2 = 0.0198 mol / 2 = 0.0099 mol

The molar volume of an ideal gas at RTP is 24.45 L/mol. Therefore, the volume of hydrogen gas produced is:

Volume of hydrogen gas = number of moles of hydrogen gas x molar volume = 0.0099 mol x 24.45 L/mol = 0.242 L

Conclusion

In this article, we have discussed the balanced chemical equation for the reaction of magnesium with excess dilute hydrochloric acid at RTP and hydrogen gas given off was collected. We have also calculated the number of moles of magnesium and the theoretical yield of hydrogen gas. The balanced chemical equation is 2Mg + 2HCl → 2MgCl2 + H2.

References

Chemistry: An Atoms First Approach, by Steven S. Zumdahl
General Chemistry: Principles and Modern Applications, by Linus Pauling

Additional Information

The reaction between magnesium and hydrochloric acid is a highly exothermic reaction, releasing a large amount of heat energy.
The reaction is also highly explosive, releasing a large amount of hydrogen gas.
The reaction is often used as a demonstration of a single displacement reaction in chemistry classes.

Frequently Asked Questions

Q: What is the balanced chemical equation for the reaction of magnesium with hydrochloric acid? A: The balanced chemical equation is 2Mg + 2HCl → 2MgCl2 + H2.
Q: How many moles of magnesium were reacted with excess dilute hydrochloric acid? A: 0.0198 mol of magnesium were reacted with excess dilute hydrochloric acid.
Q: What is the theoretical yield of hydrogen gas produced? A: The theoretical yield of hydrogen gas produced is 0.0099 mol.

Glossary

Molar mass: The mass of one mole of a substance.
Moles: A unit of measurement for the amount of a substance.
Stoichiometry: The study of the quantitative relationships between reactants and products in a chemical reaction.
Ideal gas: A hypothetical gas that obeys the ideal gas law.
Q&A: Balancing Chemical Equations and Stoichiometry =====================================================

Introduction

In our previous article, we discussed the balanced chemical equation for the reaction of magnesium with excess dilute hydrochloric acid at room temperature (RTP) and hydrogen gas given off was collected. In this article, we will answer some frequently asked questions related to balancing chemical equations and stoichiometry.

Q: What is the difference between a balanced and unbalanced chemical equation?

A: A balanced chemical equation has the same number of atoms of each element on both the reactant and product sides. An unbalanced chemical equation does not have the same number of atoms of each element on both the reactant and product sides.

Q: How do I balance a chemical equation?

A: To balance a chemical equation, you need to ensure that the number of atoms of each element is the same on both the reactant and product sides. You can do this by adding coefficients (numbers in front of the formulas of the reactants or products) to balance the equation.

Q: What is stoichiometry?

A: Stoichiometry is the study of the quantitative relationships between reactants and products in a chemical reaction. It involves calculating the amounts of reactants and products in a chemical reaction.

Q: How do I calculate the number of moles of a substance?

A: To calculate the number of moles of a substance, you need to know the mass of the substance and its molar mass. The molar mass is the mass of one mole of a substance.

Q: What is the molar volume of an ideal gas?

A: The molar volume of an ideal gas is the volume occupied by one mole of an ideal gas at standard temperature and pressure (STP). The molar volume of an ideal gas is 22.4 L/mol.

Q: How do I calculate the volume of a gas?

A: To calculate the volume of a gas, you need to know the number of moles of the gas and its molar volume. The volume of a gas is calculated by multiplying the number of moles of the gas by its molar volume.

Q: What is the difference between a mole and a gram?

A: A mole is a unit of measurement for the amount of a substance, while a gram is a unit of measurement for the mass of a substance.

Q: How do I calculate the mass of a substance?

A: To calculate the mass of a substance, you need to know the number of moles of the substance and its molar mass. The mass of a substance is calculated by multiplying the number of moles of the substance by its molar mass.

Q: What is the significance of balancing a chemical equation?

A: Balancing a chemical equation is important because it ensures that the number of atoms of each element is the same on both the reactant and product sides. This is necessary to ensure that the reaction is correct and that the amounts of reactants and products are accurate.

Q: How do I determine the limiting reactant in a chemical reaction?

A: To determine the limiting reactant in a chemical reaction, you need to know the amounts of each reactant and the stoichiometry of the reaction. The limiting reactant is the reactant that is consumed first in the reaction.

Q: What is the difference between a limiting reactant and an excess reactant?

A: A limiting reactant is the reactant that is consumed first in the reaction, while an excess reactant is the reactant that is present in excess of the amount required to react with the limiting reactant.