Answer:
6.40 grams O2
Explanation:
To find the mass, you first need the conversion factor that converts moles to grams. This conversion factor is the molar mass of the molecule, and it can be calculated using the values on the periodic table. Since there are two oxygen atoms in O2, the molar mass of oxygen (16.00 g/mol) should be doubled to 32.00 g/mol. Next, since 0.200 moles O2 is what you are trying to convert, you start with this value. Then, you multiply it by the conversion factor, making sure the units cancel out so that you are left with grams. The answer should have 3 sig figs because 0.200 moles also has 3 sig figs.
32.00 g O2
0.200 moles O2 x ----------------------- = 6.40 g O2
1 mole
