Three balloons filled with three different gaseous compounds each have a volume of 22.4 L at STP. Would these balloons have the same mass? Would they contain the same number of molecules? Explain.

A. No; B. yes

Explanation:

A. Mass

The balloons contain different gases, which will have different densities.

Mass = volume * density

m = V * D

However, the volume is the same for all three balloons.

Thus m = kD

And the mass of the gas is directly proportional to the density.

Since the density varies, the mass varies.

B. Number of molecules

This is Avogadro's Hypothesis:

At the same conditions of temperature, equal volumes of gases contain the same number of molecules.