# What is the volume of 2 mol of oxygen, O_2, at STP?

Feb 29, 2016

You need to specify (i) a pressure, and (ii) a temperature, before the molar quantity can be calculated.

#### Explanation:

If we assume standard laboratory conditions, $25$ ""^@C and $1$ $a t m$ (or thereabouts; the standard is slightly different now!), $2 L$ dioxygen gas represents, $\frac{2 L}{25.4 \cdot L \cdot m o {l}^{-} 1}$ ""approx 1/12*mol .

Feb 29, 2016

Assuming that the gas is at standard temperature and pressure (STP), one mole of any gas occupies $22.4$ $L$. This means the number of moles of ${O}_{2}$ is $\frac{2}{22.4} = 0.089$ $m o l$.
The Ideal Gas Law makes certain assumptions about the gases: that the particles are very tiny and featureless and that there is no force acting between them. If these assumptions are correct, then one mole of any gas will occupy $22.4$ $L$ at STP.
The assumptions are not quite the case for ${O}_{2}$, but the deviations from it are small enough that we can still use this approach and receive an accurate answer.