Question

The number of atoms in 4.25 g of $NH_3$ is approximately

• A. $4 \times 10^{23}$
• B. $2 \times 10^{23}$
• C. $1 \times 10^{23}$
• D. $6 \times 10^{23}$

Answer 1

The Correct Option is D

To determine the number of atoms in 4.25 g of \(NH_3\), we need to follow these steps: 

Find the molar mass of \(NH_3\):

• Nitrogen (N) has an atomic mass of approximately 14 g/mol.
• Hydrogen (H) has an atomic mass of approximately 1 g/mol.
• The molar mass of \(NH_3\) is calculated as follows:

Calculate the number of moles of \(NH_3\) in 4.25 g:

1. \(\text{Number of moles} = \frac{\text{Mass (g)}}{\text{Molar mass (g/mol)}} = \frac{4.25}{17} = 0.25 \, \text{mol}\)

Use Avogadro's number to find the number of molecules of \(NH_3\):

1. \(0.25 \, \text{mol} \times 6.022 \times 10^{23} \, \text{molecules/mol} = 1.5055 \times 10^{23} \, \text{molecules}\)

Determine the number of atoms from the molecules of \(NH_3\):

• Each molecule of \(NH_3\) contains 1 nitrogen atom and 3 hydrogen atoms, making a total of 4 atoms.
• The number of atoms is calculated as follows:

Thus, the number of atoms in 4.25 g of \(NH_3\) is approximately \(6 \times 10^{23}\), which matches the correct answer.