# Convert A) 10 atoms of C to mol C B) 5.1x10^22 atoms Cu to grams?

Jul 15, 2017

$a .$ "Moles of carbon"=("10 carbon atoms")/(6.0221xx10^23*"carbon atoms"*mol^-1)

#### Explanation:

And thus $a . = 6.0221 \times {10}^{-} 22 \cdot m o l$ (which is not a great molar quantity!)........

$b .$ On the other hand, we know that ${N}_{A} \equiv 6.0221 \times {10}^{23} \cdot \text{copper atoms}$ have a mass of $63.55 \cdot g$. How do we know this?

And so we take the product............

$\left(5.1 \times {10}^{22} \cdot \text{copper atoms"xx63.55*g*mol^-1)/(6.0221xx10^23*"copper atoms} \cdot m o {l}^{-} 1\right) \ldots \ldots$ which quotient gives an answer with units of mass as required.......

$\cong 5.5 \cdot g$....... Do you agree?