What is the mass of oxygen in an oxygen tank at 20 C if the tank has a volume of 0.20 m3 and the oxygen pressure in the tank is 4.0 105 N/m2 (mass of one mole of one mole of oxygen is 16 g and the universal gas constant is 8.31 N m mol-1 K-1).

530 g

Explanation:

Ideal gas law:

PV = nRT

(4.0*10⁵ Pa) (0.20 m³) = n (8.31 Pa m³ / mol / K) (20+273.15 K)

n = 32.8 mol

Find the mass using the molar mass:

32.8 mol * (16 g / mol) = 525 g

Rounded to two significant figures, the mass is 530 g.

Note: I used the molar mass provided, but oxygen is usually in a diatomic state (O₂), which would make the molar mass 32 g/mol.