# Aballoon contains 6.0 moles of helium. A hole in the balloon lets 4.0 moles of helium escape the balloon. How many atoms of m remain in the balloon?

Sep 3, 2016

Now of course you wanted the number of atoms remaining in the balloon. But the use of a $\text{mole}$ specifies that number.
One mole of stuff specifies $6.022 \times {10}^{23}$ individual items of that stuff. To make things easier I could write $6.022 \times {10}^{23} = {N}_{A} \text{ Avogadro's number}$, which is something that would be recognized by all chemists (including you!).
So, I am left with $2 \times {N}_{A}$ helium atoms (of course helium is a mono-atomic gas). You can do the arithmetic if you like. Can you tell me the mass of gas left in the balloon?