# A gas mixture has 2 atm He, 4.8 atm Xe, and 1.9 atm O_2. Which gas takes up the most volume in a total of 456 mL?

May 10, 2016

#### Answer:

Interesting question, and I think your examiner is trying to be malicious. The answer required is that ALL the gases occupy equal volume.

#### Explanation:

Dalton's law of partial pressure clearly states that in a gaseous mixture, the pressure exerted by a component is the same as the pressure it would exert if it ALONE occupied the container.

So, given the above, to ask which gas occupies the most volume is a non-sequitir. All the gases occupy an equal volume, and, as stated, this volume is $456 \cdot m L$. The total pressure is of course $\left(2 + 4.8 + 1.9\right) \cdot a t m$, but this is not what the question asked.

PS I actually like this question, so I am going to steal it for my A2 class as a concept type of question to establish Dalton's Law. I bet it will fool most of the little blighters.