# If 91.5 mol of an ideal gas occupies 69.5 L at 31.00°C, what is the pressure of the gas?

You will need to use the Ideal Gas Law to solve this problem:

$P V = n R T$

#### Explanation:

To find pressure $\left(P\right)$, derive from the Ideal Gas Law:

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

Gather up your known values, and plug them into the equation.

There are a few points to make here, Temperature $\left(T\right)$ must be converted to Kelvin.

$R$ = Ideal Gas Constant. This can have many forms. The one I used below is the one that I am most familiar with. Be aware of this though, and check which value you should be using per your curriculum.

$n = 91.5 m o l$
$V = 69.5 L$
T = 31.0°C + (273.15K) = 304.15K
$R = 8.314 \frac{J}{m o l \cdot K}$

Finally,

$P = \frac{\left(91.5 m o l\right) \left(8.314 \frac{J}{m o l \cdot K}\right) \left(304.15 K\right)}{69.5 L}$

$P = \left(x\right) a t m$