To determine the mass of helium given a certain number of moles, we need to use the molar mass of helium. The molar mass allows us to convert between the number of moles and the mass of an element or compound.
Firstly, we know the following information:
- The number of moles of helium (He) is given as 12.3 moles.
- The molar mass of helium (He) is 4.0026 grams per mole (g/mol).
The formula to calculate the mass from the number of moles is:
[tex]\[ \text{Mass (g)} = \text{Number of moles} \times \text{Molar mass (g/mol)} \][/tex]
Plugging in the given values:
[tex]\[ \text{Mass of helium} = 12.3 \, \text{moles} \times 4.0026 \, \text{g/mol} \][/tex]
When we carry out this multiplication:
[tex]\[ \text{Mass of helium} = 49.231980 \, \text{grams} \][/tex]
Looking at the options provided:
- 0.325 g He
- 3.07 g He
- 49.2 g He
- 74.0 g He
The calculated mass of helium is approximately 49.231980 grams, which rounds to 49.2 grams when expressed to one decimal place. Therefore, the correct answer is:
49.2 g He
