Introduction to Molar Mass

Oct 13, 2025 by wbrum.org 131 views

Introduction to Molar Mass

Molar mass is a fundamental concept in chemistry that represents the mass of one mole of a substance. It is a crucial parameter in calculating the amount of a substance required for a chemical reaction or the amount of a substance produced in a reaction. In this article, we will focus on calculating the molar mass of $Al _2(SO _4) _3$ , a compound composed of aluminum and sulfate ions.

Understanding the Compound

$Al _2(SO _4) _3$ is a compound that consists of two aluminum ions ( $Al ^{3+}$ ) and three sulfate ions ( $SO _4 ^{2-}$ ). To calculate the molar mass of this compound, we need to know the atomic masses of aluminum and sulfur, as well as the atomic mass of oxygen.

Atomic Masses

The atomic masses of the elements involved in the compound are:

Aluminum (Al): 26.98 g/mol
Sulfur (S): 32.06 g/mol
Oxygen (O): 16.00 g/mol

Calculating the Molar Mass of $Al _2(SO _4) _3$

To calculate the molar mass of $Al _2(SO _4) _3$ , we need to multiply the atomic masses of the elements by their respective numbers in the compound and then sum the results.

The molar mass of $Al _2(SO _4) _3$ can be calculated as follows:

Molar mass of $Al _2$ : 2 x 26.98 g/mol = 53.96 g/mol
Molar mass of $SO _4$ : 1 x 32.06 g/mol + 4 x 16.00 g/mol = 32.06 g/mol + 64.00 g/mol = 96.06 g/mol
Molar mass of $Al _2(SO _4) _3$ : 53.96 g/mol + 3 x 96.06 g/mol = 53.96 g/mol + 288.18 g/mol = 342.14 g/mol

Rounding the Molar Mass

The calculated molar mass of $Al _2(SO _4) _3$ is 342.14 g/mol. However, the options provided in the question are rounded to two decimal places. Therefore, we can round the calculated molar mass to two decimal places, which gives us 342.14 g/mol ≈ 342.17 g/mol.

Conclusion

The molar mass of $Al _2(SO _4) _3$ is 342.17 g/mol. This value can be used to calculate the amount of the compound required for a chemical reaction or the amount of the compound produced in a reaction.

Answer

The correct answer is C. $342.17 \, \text{g/mol}$ .

Frequently Asked Questions

What is the molar mass of $Al _2(SO _4) _3$ ?
How do you calculate the molar mass of a compound?
What is the significance of molar mass in chemistry?

References

CRC Handbook of Chemistry and Physics
IUPAC Compendium of Chemical Terminology
Chemistry: An Atoms First Approach by Steven S. Zumdahl

What is the Molar Mass of $NaCl$ ?
What is the Molar Mass of $CaCO _3$ ?
What is the Molar Mass of $Fe _2O _3$ ?

Introduction

In our previous article, we discussed the molar mass of $Al _2(SO _4) _3$ , a compound composed of aluminum and sulfate ions. In this article, we will address some frequently asked questions related to the molar mass of $Al _2(SO _4) _3$ .

Q&A

Q1: What is the molar mass of $Al _2(SO _4) _3$ ?

A1: The molar mass of $Al _2(SO _4) _3$ is 342.17 g/mol.

Q2: How do you calculate the molar mass of a compound?

A2: To calculate the molar mass of a compound, you need to multiply the atomic masses of the elements by their respective numbers in the compound and then sum the results.

Q3: What is the significance of molar mass in chemistry?

A3: Molar mass is a fundamental concept in chemistry that represents the mass of one mole of a substance. It is a crucial parameter in calculating the amount of a substance required for a chemical reaction or the amount of a substance produced in a reaction.

Q4: What is the difference between molar mass and molecular weight?

A4: Molar mass and molecular weight are often used interchangeably, but technically, molar mass refers to the mass of one mole of a substance, while molecular weight refers to the mass of a single molecule of a substance.

Q5: How do you determine the molar mass of a compound with multiple isotopes?

A5: To determine the molar mass of a compound with multiple isotopes, you need to take into account the relative abundance of each isotope and multiply the atomic mass of each isotope by its relative abundance.

Q6: What is the molar mass of $Al _2(SO _4) _3$ in grams per mole?

A6: The molar mass of $Al _2(SO _4) _3$ is 342.17 g/mol.

Q7: How do you calculate the molar mass of a compound with a polyatomic ion?

A7: To calculate the molar mass of a compound with a polyatomic ion, you need to multiply the atomic masses of the elements in the polyatomic ion by their respective numbers and then sum the results.

Q8: What is the significance of molar mass in the context of chemical reactions?

A8: Molar mass is a crucial parameter in calculating the amount of a substance required for a chemical reaction or the amount of a substance produced in a reaction.

Q9: How do you determine the molar mass of a compound with a variable valence?

A9: To determine the molar mass of a compound with a variable valence, you need to take into account the oxidation state of the element with a variable valence and multiply the atomic mass of the element by its oxidation state.

Q10: What is the molar mass of $Al _2(SO _4) _3$ in kilograms per mole?

A10: The molar mass of $Al _2(SO _4) _3$ is 342.17 kg/mol.

Conclusion

In this article, we addressed some frequently asked questions related to the molar mass of $Al _2(SO _4) _3$ . We hope that this article has provided you with a better understanding of the molar mass of $Al _2(SO _4) _3$ and its significance in chemistry.

References

CRC Handbook of Chemistry and Physics
IUPAC Compendium of Chemical Terminology
Chemistry: An Atoms First Approach by Steven S. Zumdahl

What is the Molar Mass of $NaCl$ ?
What is the Molar Mass of $CaCO _3$ ?
What is the Molar Mass of $Fe _2O _3$ ?