What is the mass of 7.241023 formula units of barium oxide?

To calculate the mass of 7.241023 formula units of barium oxide (BaO), first determine the molar mass of BaO. The molar mass is approximately 153.33 g/mol (137.33 g/mol for Ba and 16.00 g/mol for O). Since 1 mole contains (6.022 \times 10^{23}) formula units (Avogadro's number), the mass can be calculated using the formula:

[ \text{mass} = \left(\frac{7.241023}{6.022 \times 10^{23}}\right) \times 153.33 , \text{g} ]

This results in a mass of approximately (1.84 \times 10^{-21}) grams.