7. If there are \( 3.00 \times 10^{23} \) formula units of feCliz present a. How many moles is this? b. How many grams would this be?

To convert formula units to moles, you can use Avogadro's number, which is approximately \( 6.022 \times 10^{23} \) formula units per mole. So, to find the moles of \( \text{FeCl}_2 \), you would calculate: \[ \text{Moles} = \frac{3.00 \times 10^{23}}{6.022 \times 10^{23}} \approx 0.498 \, \text{moles} \] To find the mass in grams, you first need the molar mass of \( \text{FeCl}_2 \), which is about \( 126.75 \, \text{g/mol (Fe)} + 2 \times 35.45 \, \text{g/mol (Cl)} = 126.75 + 70.90 = 197.65 \, \text{g/mol} \). Now calculate the mass: \[ \text{Mass} = 0.498 \, \text{moles} \times 197.65 \, \text{g/mol} \approx 98.5 \, \text{grams} \]