# What volume in liters does 0.136 g of O2 occupy at 20.0 degree C and 748 torr?

##### 1 Answer
Mar 30, 2015

The volume will be $\text{0.104 L}$.

You're dealing with a sample of oxygen gas, ${O}_{2}$, at a certain temperature, $\text{20"^@"C}$, and pressure, $\text{748 torr}$. To solve for the volume it occupies, use the ideal gas law equation, $P V = n R T$.

Use oxygen's molar mass to determine th number of moles you have in that sample first

0.136cancel("g") * "1 mole"/(32.0cancel("g")) = "0.00425 moles"

Now plug all your values into the ideal gas law equation - do not forget to convert degrees Celsius to Kelvin and torr to atm

$P V = n R T \implies V = \frac{n R T}{P}$

$V = \left(0.00425 \cancel{\text{moles") * 0.082(cancel("atm") * "L")/(cancel("mol") * cancel("K")) * (273.15 + 20)cancel("K"))/(748/760cancel("atm}}\right)$

$V = \text{0.1038 L}$

Rounded to three sig figs, the answer will be

$V = \textcolor{g r e e n}{\text{0.104 L}}$