The mass of a balloon is 0.02g before it is filled with air. After it is blown up with air the mass is 0.04g. Assuming oxygen makes up 21% of air, calculate the number of moles of oxygen in the balloon.
Mass of oxygen in balloon = 0.02 x 0.21 Mr (O2) = 16 x 2 = 32 Moles = mass / Mr = (0.02 x 0.21) / 32 = 1.31 x 10^4 moles Or 0.000131 moles
