# What is the mass of 3.8*10^24 atoms of argon?

Oct 17, 2016

$3.8 \times {10}^{24}$ argon atoms have a mass of approx. $250 \cdot g$.

#### Explanation:

$6.022 \times {10}^{23}$ argon atoms have a mass of $39.95 \cdot g$. How do I know this? Well, $6.022 \times {10}^{23}$ is $\text{Avogadro's number}$, and the Periodic Table lists the mass of $\text{Avogadro's number of each atom}$.

And thus we calculate the product:

$\left(3.8 \times {10}^{24} {\text{ argon atoms")/(6.022xx10^23" argon atoms mol}}^{-} 1\right) \times 39.95 \cdot g \cdot m o {l}^{-} 1$ $=$ ??g

Argon is often used in the laboratory to provide a protective blanket of inert gas for reactions with air and water sensitive reagents. Why should argon be unreactive towards the reagents?