Calculating Molar Mass of Aluminum Hydroxide

Oct 13, 2025 by wbrum.org 95 views

Understanding Mass Percent

Mass percent is a measure of the amount of a particular element in a compound. It is calculated by dividing the mass of the element by the total mass of the compound and multiplying by 100. In this case, we are asked to find the mass percent of aluminum in aluminum hydroxide, $$Al(OH)_3$$.

Calculating Molar Mass of Aluminum Hydroxide

To calculate the mass percent of aluminum, we first need to calculate the molar mass of aluminum hydroxide. The molar masses of the elements in the compound are given as:

Aluminum (Al): 26.98 g/mol
Oxygen (O): 16.00 g/mol
Hydrogen (H): 1.0079 g/mol

The formula for aluminum hydroxide is $$Al(OH)_3$$. This means that there is one aluminum atom, three oxygen atoms, and three hydrogen atoms in each molecule of aluminum hydroxide.

Calculating Molar Mass of Aluminum Hydroxide

To calculate the molar mass of aluminum hydroxide, we need to multiply the molar mass of each element by the number of atoms of that element in the compound and add them together.

Molar mass of aluminum hydroxide = (1 x molar mass of Al) + (3 x molar mass of O) + (3 x molar mass of H) Molar mass of aluminum hydroxide = (1 x 26.98) + (3 x 16.00) + (3 x 1.0079) Molar mass of aluminum hydroxide = 26.98 + 48.00 + 3.0237 Molar mass of aluminum hydroxide = 78.0037 g/mol

Calculating Mass Percent of Aluminum

Now that we have the molar mass of aluminum hydroxide, we can calculate the mass percent of aluminum. To do this, we need to divide the mass of aluminum by the molar mass of aluminum hydroxide and multiply by 100.

Mass percent of aluminum = (mass of aluminum / molar mass of aluminum hydroxide) x 100 Mass percent of aluminum = (26.98 / 78.0037) x 100 Mass percent of aluminum = 0.3460 x 100 Mass percent of aluminum = 34.60%

Conclusion

The mass percent of aluminum in aluminum hydroxide is 34.60%. This means that 34.60% of the mass of aluminum hydroxide is made up of aluminum.

Answer

The correct answer is A. 34.59%.

Discussion

This problem requires the student to understand the concept of mass percent and how to calculate it. The student must also be able to calculate the molar mass of a compound and use it to calculate the mass percent of an element in that compound. This problem is relevant to chemistry because it requires the student to apply the concept of mass percent to a real-world scenario.

Additional Information

The molar mass of aluminum hydroxide is 78.0037 g/mol.
The mass percent of aluminum in aluminum hydroxide is 34.60%.
The correct answer is A. 34.59%.

References

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

Keywords

Mass percent
Molar mass
Aluminum hydroxide
Chemistry
Q&A: Calculating Mass Percent of Aluminum in Aluminum Hydroxide ================================================================

Frequently Asked Questions

Q: What is mass percent?

A: Mass percent is a measure of the amount of a particular element in a compound. It is calculated by dividing the mass of the element by the total mass of the compound and multiplying by 100.

Q: How do I calculate the molar mass of a compound?

A: To calculate the molar mass of a compound, you need to multiply the molar mass of each element by the number of atoms of that element in the compound and add them together.

Q: What is the molar mass of aluminum hydroxide?

A: The molar mass of aluminum hydroxide is 78.0037 g/mol.

Q: How do I calculate the mass percent of an element in a compound?

A: To calculate the mass percent of an element in a compound, you need to divide the mass of the element by the molar mass of the compound and multiply by 100.

Q: What is the mass percent of aluminum in aluminum hydroxide?

A: The mass percent of aluminum in aluminum hydroxide is 34.60%.

Q: Why is it important to calculate mass percent?

A: Calculating mass percent is important because it allows you to determine the amount of a particular element in a compound. This is useful in a variety of applications, including chemistry and materials science.

Q: What are some common mistakes to avoid when calculating mass percent?

A: Some common mistakes to avoid when calculating mass percent include:

Not using the correct molar masses of the elements
Not multiplying the molar mass of each element by the correct number of atoms
Not adding the molar masses of the elements together correctly
Not dividing the mass of the element by the molar mass of the compound correctly

Q: How can I practice calculating mass percent?

A: You can practice calculating mass percent by working through example problems and using online resources, such as calculators and worksheets.

Q: What are some real-world applications of mass percent?

A: Some real-world applications of mass percent include:

Chemistry: Mass percent is used to determine the amount of a particular element in a compound.
Materials science: Mass percent is used to determine the composition of materials.
Biology: Mass percent is used to determine the amount of a particular element in a biological sample.

Conclusion

Calculating mass percent is an important skill in chemistry and materials science. By understanding how to calculate mass percent, you can determine the amount of a particular element in a compound and apply this knowledge to a variety of real-world applications.

Additional Information

The molar mass of aluminum hydroxide is 78.0037 g/mol.
The mass percent of aluminum in aluminum hydroxide is 34.60%.
Calculating mass percent is an important skill in chemistry and materials science.

References

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

Keywords

Mass percent
Molar mass
Aluminum hydroxide
Chemistry