Final answer:
The mass of 9.00 x 10^22 formula units of magnesium oxide is approximately 6.02 grams. This calculation involves finding the number of moles from the formula units and then multiplying by the molar mass of MgO.
Step-by-step explanation:
To calculate the mass of 9.00 x 1022 formula units of magnesium oxide, we need to first use Avogadro's number to find the number of moles of magnesium oxide represented by this number of units. Avogadro's number is 6.022 x 1023 formula units per mole. Therefore, we divide the number of formula units by Avogadro's number to get the number of moles.
Number of moles = 9.00 x 1022 / 6.022 x 1023 = 0.1495 moles
Next, we need to find the molar mass of magnesium oxide (MgO). Magnesium has an average atomic mass of approximately 24.305 amu and oxygen has a mass of about 16.00 amu. Thus, the molar mass of MgO is 24.305 + 16.00 = 40.305 grams per mole.
Finally, to find the mass in grams, we multiply the number of moles by the molar mass of magnesium oxide:
Mass of MgO = 0.1495 moles x 40.305 g/mole = 6.02 grams