Calculating the Number of Moles in a Sample

Oct 13, 2025 by pynkocean.com 84 views

In chemistry, the mole is a fundamental unit of measurement that represents a specific amount of a substance. It is defined as the amount of a substance that contains as many particles (atoms, molecules, or ions) as there are atoms in 0.012 kilograms of carbon-12. The mole is a crucial concept in chemistry, as it allows us to relate the amount of a substance to its mass and the number of particles it contains.

Calculating the Number of Moles in a Sample

To calculate the number of moles in a sample of neon containing $2.4 \cdot 10^{24}$ atoms, we need to use the Avogadro's number, which is $6.022 \cdot 10^{23}$ particles per mole. This number represents the number of particles in one mole of a substance.

Step 1: Understand the Given Information

We are given that the sample of neon contains $2.4 \cdot 10^{24}$ atoms. This is the number of particles in the sample.

Step 2: Use Avogadro's Number to Calculate the Number of Moles

To calculate the number of moles in the sample, we need to divide the number of particles in the sample by Avogadro's number.

Number of moles = Number of particles / Avogadro's number

Step 3: Perform the Calculation

Number of moles = $2.4 \cdot 10^{24}$ / $6.022 \cdot 10^{23}$

Number of moles = $3.98 \cdot 10^{0}$

Number of moles = 3.98

Rounding the Answer

Since the answer is not an exact multiple of 10, we need to round it to the nearest whole number. However, in this case, the answer is already a whole number, so we can leave it as is.

Conclusion

Therefore, the number of moles in a sample of neon containing $2.4 \cdot 10^{24}$ atoms is approximately 4 moles.

Comparison with the Given Options

Comparing our answer with the given options, we can see that the correct answer is option C, which is 4.0 moles.

Key Takeaways

The mole is a fundamental unit of measurement in chemistry that represents a specific amount of a substance.
Avogadro's number is $6.022 \cdot 10^{23}$ particles per mole.
To calculate the number of moles in a sample, we need to divide the number of particles in the sample by Avogadro's number.
The number of moles in a sample of neon containing $2.4 \cdot 10^{24}$ atoms is approximately 4 moles.

Additional Practice Problems

Calculate the number of moles in a sample of oxygen containing $1.2 \cdot 10^{25}$ molecules.
Calculate the number of moles in a sample of nitrogen containing $3.6 \cdot 10^{23}$ atoms.
Calculate the number of moles in a sample of carbon dioxide containing $2.1 \cdot 10^{24}$ molecules.

Answer Key

$2.0 \cdot 10^{1}$ moles
$5.9 \cdot 10^{-1}$ moles
$3.5 \cdot 10^{0}$ moles
Frequently Asked Questions (FAQs) about Moles in Chemistry ================================================================

In this article, we will address some of the most common questions related to moles in chemistry. Whether you are a student, a teacher, or simply someone interested in chemistry, this article will provide you with a comprehensive understanding of moles and their applications.

Q: What is a mole in chemistry?

A: A mole is a fundamental unit of measurement in chemistry that represents a specific amount of a substance. It is defined as the amount of a substance that contains as many particles (atoms, molecules, or ions) as there are atoms in 0.012 kilograms of carbon-12.

Q: How is Avogadro's number related to moles?

A: Avogadro's number is $6.022 \cdot 10^{23}$ particles per mole. This number represents the number of particles in one mole of a substance. To calculate the number of moles in a sample, we need to divide the number of particles in the sample by Avogadro's number.

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

A: A mole and a gram are two different units of measurement. A mole represents a specific amount of a substance, while a gram represents a specific mass of a substance. For example, one mole of carbon-12 has a mass of 12 grams.

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

A: To calculate the number of moles in a sample, you need to follow these steps:

Determine the number of particles in the sample.
Divide the number of particles by Avogadro's number.
The result is the number of moles in the sample.

Q: What is the significance of Avogadro's number?

A: Avogadro's number is a fundamental constant in chemistry that allows us to relate the amount of a substance to its mass and the number of particles it contains. It is a crucial concept in chemistry, as it enables us to calculate the number of moles in a sample.

Q: Can I use Avogadro's number to calculate the number of particles in a sample?

A: Yes, you can use Avogadro's number to calculate the number of particles in a sample. To do this, you need to multiply the number of moles in the sample by Avogadro's number.

Q: What are some common applications of moles in chemistry?

A: Moles are used in a wide range of applications in chemistry, including:

Calculating the number of particles in a sample
Determining the mass of a substance
Understanding chemical reactions and stoichiometry
Calculating the number of moles in a mixture

Q: How do I convert between moles and grams?

A: To convert between moles and grams, you need to use the molar mass of the substance. The molar mass is the mass of one mole of a substance. To convert from moles to grams, you need to multiply the number of moles by the molar mass. To convert from grams to moles, you need to divide the mass by the molar mass.

Q: What is the relationship between moles and the ideal gas law?

A: The ideal gas law is a fundamental equation in chemistry that relates the pressure, volume, and temperature of a gas to the number of moles of gas present. The ideal gas law is expressed as PV = nRT, where P is the pressure, V is the volume, n is the number of moles, R is the gas constant, and T is the temperature.

Conclusion

In this article, we have addressed some of the most common questions related to moles in chemistry. We have discussed the definition of a mole, Avogadro's number, and its significance in chemistry. We have also provided examples of how to calculate the number of moles in a sample and how to convert between moles and grams. Finally, we have discussed the relationship between moles and the ideal gas law. We hope that this article has provided you with a comprehensive understanding of moles and their applications in chemistry.