How many moles of Cu are in 1.48*10^25 Cu atoms?

Mar 30, 2018

There are $\text{24.6 mol Cu atoms}$ in $1.48 \times {10}^{25}$ $\text{Cu atoms}$.
One mole of atoms contains $6.022 \times {10}^{23}$ atoms. You may recognize this as Avogadro's number $\left({N}_{\text{A}}\right)$. Divide the given number of atoms by (6.022xx10^23"atoms")/"mol". Since (6.022xx10^23"atoms")/"mol" is a fraction, divide by multiplying by its reciprocal.
1.48xx10^25color(red)cancel(color(black)("atoms Cu"))xx(1"mol Cu")/(6.022xx10^23color(red)cancel(color(black)("atoms Cu")))="24.6 mol Cu" (rounded to three significant figures)
There are $\text{24.6 mol Cu atoms}$ in $1.48 \times {10}^{25}$ $\text{Cu atoms}$.