How many milligrams are in 0.250 mmole Fe2O3 (ferric oxide). (A.wt O= 16

g/mole , Fe =56.85 g/mole)

To find the number of milligrams in 0.250 mmole Fe2O3, we need to calculate the molar mass of Fe2O3 first.

The molar mass of Fe2O3 can be calculated as follows:
Fe: atomic weight = 56.85 g/mole
O: atomic weight = 16 g/mole x 3 (number of oxygen atoms in Fe2O3) = 48 g/mole

Adding the molar masses of Fe and O gives us:
56.85 g/mole (Fe) + 48 g/mole (O) = 104.85 g/mole

Now, we can calculate the number of milligrams in 0.250 mmole Fe2O3:
0.250 mmole x 104.85 g/mole x (1000 mg / g) = 26.21 mg

Therefore, there are approximately 26.21 milligrams in 0.250 mmole of Fe2O3.