Molecular Count and Mass Calculation for 0.750 Moles of Hydrogen

Molecular counting and mass calculation are essential in chemistry, particularly when dealing with molecules of elements such as hydrogen. Let's explore how to calculate the number of molecules in 0.750 moles of H2 (dihydrogen) and the corresponding mass.

Understanding Moles and Avogadro's Number

Moles are a unit in chemistry used to signify a certain number of particles, such as atoms, molecules, or ions. Avogadro's number, which is approximately 6.022 x 1023, represents the number of individual particles in one mole of a substance.

Calculating the Number of Molecules in 0.750 Moles of Hydrogen

To determine the number of molecules in 0.750 moles of hydrogen gas (H2), we use the relationship between moles, Avogadro's number, and the given quantity of moles.

The formula to calculate the number of molecules is:

Number of molecules moles × Avogadro's number

Given:

Number of moles 0.750 moles Avogadro's number 6.022 x 1023 molecules/mole

Thus, the calculation is:

Number of molecules 0.750 moles × 6.022 x 1023 molecules/mole

Number of molecules 4.5165 x 1023 molecules

Rounding to a reasonable significant figure, we get:

Number of molecules ≈ 4.5 x 1023 molecules

Converting Molecules to Atoms

Since each molecule of hydrogen gas (H2) consists of two atoms, the total number of atoms in 0.750 moles of H2 can be calculated as follows:

Total number of atoms Number of molecules × 2

Total number of atoms 4.5 x 1023 × 2

Total number of atoms 9.0 x 1023 atoms

Mass Calculation

To find the mass of 0.750 moles of hydrogen gas (H2), we need to know the molar mass of hydrogen gas. The molar mass of hydrogen (H) is approximately 1 g/mol, so the molar mass of H2 is 2 g/mol.

Formula for mass calculation:

Mass moles × molar mass

Given:

No. of moles 0.750 moles Molar mass of H2 2 g/mol

Mass calculation:

Mass 0.750 moles × 2 g/mol

Mass 1.5 g

In summary:

Number of molecules in 0.750 moles of H2: 4.5 x 1023 molecules Total number of atoms in 0.750 moles of H2: 9.0 x 1023 atoms Mass of 0.750 moles of H2: 1.5 g

Conclusion

This demonstration provides a clear method for calculating the number of molecules and atoms in 0.750 moles of hydrogen gas, as well as the corresponding mass. Understanding these concepts is crucial for advanced chemistry and chemical engineering calculations.