# How many molecules are in 4.5 L of CO_2 at STP?

May 1, 2016

$\frac{4.5 \cdot L}{22.4 \cdot L \cdot m o {l}^{-} 1}$ $\times$ ${N}_{A}$, where ${N}_{A} = \text{ Avogadro's number}$

#### Explanation:

We assume ideality, and recall that at $\text{STP}$ 1 mole of ideal gas occupies a volume of $22.4 \cdot L$. We also know that ${N}_{A} = \text{ Avogadro's number}$ $=$ $6.02214 \times {10}^{23} \cdot m o {l}^{-} 1$

So $\frac{4.5 \cdot L}{22.4 \cdot L \cdot m o {l}^{-} 1}$ $\times$ $6.02214 \times {10}^{23} \cdot m o {l}^{-} 1$ $=$

"approx. "1/5xxN_A?

You can do the arithmetic.

How many atoms are there in this quantity?