A sample of diatomic gas A has three times the mass of an equal volume of gas B under the same conditions. What is the ratio of the atomic mass of A to that of B?

1 Answer
Mar 15, 2017

The atomic mass of "A" is 1.5 times the atomic mass of "B".

Explanation:

Let's say that the formula of Gas A is "A"_2 and the formula of Gas B is "B".

Avogadro's Law tells us that equal volumes of gases at the same temperature and pressure contain equal numbers of molecules.

Thus, if Gas A has three times the mass of an equal volume of Gas B, a molecule of Gas A must have three times the mass of an atom of Gas B.

But a molecule of Gas A contains two atoms of "A".

Hence each atom of "A" has 3/2 = 1.5 times the mass of an atom of "B".