# How many helium atoms are there in a helium blimp containing 535 kg of helium?

Sep 15, 2017

Approx.....$8 \times {10}^{28} \cdot \text{helium atoms}$

#### Explanation:

We work out (i) the molar quantity of helium gas....

$\text{Moles of helium} = \frac{535 \cdot k g \times {10}^{3} \cdot g \cdot k {g}^{-} 1}{4.0 \cdot g \cdot m o {l}^{-} 1} = 133750 \cdot m o l .$

And then (ii) we mulitply this molar quantity by Avogadro's number....${N}_{A} = 6.022 \times {10}^{23} \cdot m o {l}^{-} 1$ to get the number of helium atoms.....

$6.022 \times {10}^{23} \cdot m o {l}^{-} 1 \times 133750 \cdot m o l = \text{an unfeasibly large number}$.