For this problem we assume that oxygen is an ideal gas. So, we use the equation PV=nRT where P is pressure, V is the volume, n is the number of moles, R is a universal constant and T is the temperature. We first solve for the number of moles n. Then, using the molar mass of oxygen we convert it to grams.
PV=nRT
n = PV / RT
n = 3.23 (8.5) / 0.08206 (32+273.15)
n = 1.0964 mol
mass = 1.0964 mol (32g / 1 mol) = 35.09 g O2
