Four balloons, each with a mass of 10.0 g, are inflated to a volume of 20.0 L, each with a different gas: helium, neon, carbon monoxide, or nitrogen monoxide. If the temperature is 25.0°C and the atmospheric pressure is1.00 atm, what is the density of each filled balloon? (Note: The density of the filled balloon refers to both the contents of the balloon and the balloon itself.)

On temperature 25°C (298,15K) and pressure of 1 atm each gas has same amount of substance:

n (gas) = p·V : R·T = 1 atm · 20L : 0,082 L · atm/K · mol · 298,15 K

n (gas) = 0,82 mol.

1) m (He) = 0,82 mol · 4 g/mol = 3,28 g.

d (He) = 10 g + 3,28 g : 20 L = 0,664 g/L.

2) m (Ne) = 0,82 mol · 20,17 g/mol = 16,53 g.

d (Ne) = 26,53 g : 20 L = 1,27 g/L.

3) m (CO) = 0,82 mol ·28 g/mol = 22,96 g.

d (CO) = 32,96 g : 20L = 1,648 g/L.

4) m (NO) = 0,82 mol ·30 g/mol = 24,6 g.

d (NO) = 34,6 g : 20 L = 1,73 g/L.