Answer:
The balanced equation for the combustion of propane is:
C3H8 + 5O2 --> 3CO2 + 4H2O
So for every propane molecule, we need 5 oxygen molecules.
To calculate the number of oxygen molecules required to burn 2.56 x 10^22 propane molecules, we need to multiply the number of propane molecules by the ratio of oxygen molecules to propane molecules.
Ratio of O2 to C3H8 = 5:1
Number of O2 molecules required = (5/1) x 2.56 x 10^22 = 1.28 x 10^23
Now we can convert the number of oxygen molecules to grams using the molar mass of oxygen.
1 mole of O2 = 32 g
1.28 x 10^23 molecules of O2 = (1.28 x 10^23 / 6.022 x 10^23) moles of O2
Mass of O2 = (1.28 x 10^23 / 6.022 x 10^23) x 32 g
Mass of O2 = 6.82 grams
So, 6.82 grams of O2 are required to burn 2.56 x 10^22 propane molecules.