# How many mols of aluminum atoms are in #1.42 xx 10^24# atoms?

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Am I doing this right?

1.42x1024 x 26.98 = 3.83x1025

Am I doing this right?

1.42x1024 x 26.98 = 3.83x1025

##### 1 Answer

What you did was multiply the molar mass of aluminum atom by the number of atoms, which physically doesn't make sense; it gives you:

#"g"/"mol" xx "atoms" = ("g"cdot"atoms")/"mol"# .

The atoms "unit" has to *cancel* so that you get into the units of

#cancel("atoms") xx "mol"/cancel("atoms")#

How I would do it is to recall that

So if you have

That's just an estimate, but it gives you an idea of what we expect to get.

#1.42xx10^24 cancel"atoms" xx "1 mol"/(6.022xx10^23 cancel"atoms") = 14.2/6.022 = bb("2.36 mols")# of aluminum atoms.

A

Similarly, **smaller**, not larger, than your number of atoms.