Calculating Moles of Carbon in 7.2 Grams

Understanding the concept of moles and how to calculate them from the mass of a substance is fundamental in chemistry. This article explains the process of determining the number of moles in 7.2 grams of carbon, providing clarity and a clear step-by-step guide.

Introduction to Moles and Molar Mass

Moles represent a specific number of particles (atoms, molecules, ions, etc.) in a substance. One mole of any substance contains Avogadro's number of particles, approximately 6.022 x 1023. The molar mass of a substance is the mass of one mole of that substance and is the sum of the atomic masses of all atoms in the molecule.

Step-by-Step Calculation

To calculate the number of moles in 7.2 grams of carbon, we will use the following formula:

Formula

Number of moles (n) Mass of the substance (m) / Molar mass of the substance (M)

Applying the Formula to Carbon (C)

Carbon has a molar mass of 12.01 grams per mole (g/mol). Given that the mass of the substance is 7.2 grams, we can substitute these values into the formula:

n 7.2 g / 12.01 g/mol

Performing the division:

n 0.6 mol

This gives us the number of moles in 7.2 grams of carbon. To verify dimensional consistency, we note that the units cancel out correctly, leaving us with a unit of moles, which is what we desired.

Understanding the Result

The result, 0.6 moles, means that 7.2 grams of carbon contain 0.6 times Avogadro's number of carbon atoms, or approximately 3.613 x 1023 carbon atoms.

Further Exploration

Molecular Weight and Chemical Formulas: The molar mass of carbon can be derived from the periodic table, where carbon has a molar mass of 12.01 g/mol. If we were to consider a molecule of carbon dioxide (CO2) instead, the molar mass would be calculated as:

12.01 g/mol 2 x 16.00 g/mol 44.01 g/mol

Then, the number of moles in a given mass of CO2 can be calculated similarly.

Conclusion

Understanding the concept of moles and how to calculate them from the mass of a substance is crucial in chemistry. By using the given formula and the known molar masses, we can easily determine the number of moles in any given mass of a substance. In this case, we calculated that 7.2 grams of carbon amounts to 0.6 moles of carbon atoms.

Related Questions and Discussion

1. What is the molar mass of a substance, and how do you calculate it?
Molar mass is the mass of one mole of a substance. For a molecule, it is the sum of the atomic masses of all atoms in the molecule. This can be found on the periodic table.

2. Can you apply the molar mass calculation to other elements or molecules?
Yes, the same principle applies. For example, for water (H2O), the molar mass is 2 x 1 g/mol for hydrogen and 16 g/mol for oxygen, totaling 18 g/mol.

3. Why is dimensional analysis important in chemistry?
Dimensional analysis ensures that the units in a calculation are consistent and correct, helping to avoid errors and ensuring accurate results.