# A gas has a volume of 65 ml when measured at a pressure of .90 atm. If the temperature is 5°C, how many moles of the gas are there?

Apr 23, 2017

Approx. $2 \cdot m m o l$.

#### Explanation:

We use the Ideal Gas equation..........

$n = \frac{P V}{R T} = \frac{0.90 \cdot \cancel{a t m} \times 0.065 \cdot \cancel{L}}{0.0821 \cdot \cancel{L \cdot a t m \cdot {K}^{-} 1} \cdot m o {l}^{-} 1 \times 278 \cdot \cancel{K}}$

$\cong 2 \cdot m m o l$

Note that we got an answer in $\frac{1}{m o {l}^{-} 1} = \frac{1}{\frac{1}{m o l}} = m o l$ as required. The calculation is thus dimensionally consistent.