Question

The molar mass of BF3 is 67.81 g/mol. How many molecules of BF3 are there in 2 g?(1 point)
Responses

4.084×10254 point 0 8 4 times 10 to the 25th power

1.776×10221 point 7 7 6 times 10 to the 22th power

1.204×10241 point 2 0 4 times 10 to the 24th power

8.881×10218 point 8 8 1 times 10 to the 21th power

Answer 1

To find the number of molecules of BF\(_3\) in 2 g, we first need to calculate the number of moles of BF\(_3\) in that mass, and then use Avogadro's number to convert moles to molecules.

1. **Calculate the number of moles of BF\(_3\)**:
\[
\text{moles of BF}_3 = \frac{\text{mass}}{\text{molar mass}} = \frac{2 \, \text{g}}{67.81 \, \text{g/mol}} \approx 0.0295 \, \text{mol}
\]

2. **Use Avogadro's number to convert moles to molecules**:
Avogadro's number (\(6.022 \times 10^{23} \, \text{molecules/mol}\)) allows us to convert moles to molecules:
\[
\text{molecules of BF}_3 = \text{moles} \times \text{Avogadro's number} \approx 0.0295 \, \text{mol} \times 6.022 \times 10^{23} \, \text{molecules/mol} \approx 1.77 \times 10^{22} \, \text{molecules}
\]

Therefore, the closest answer from the provided options is:

**1.776×10²² molecules of BF3**.