Question

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

Answer 1

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

Explanation:

And thus `a.=6.0221xx10^-22*mol` (which is not a great molar quantity!)........

`b.` On the other hand, we know that `N_A-=6.0221xx10^23*"copper atoms"` have a mass of `63.55*g`. How do we know this?

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

`(5.1xx10^22*"copper atoms"xx63.55*g*mol^-1)/(6.0221xx10^23*"copper atoms"*mol^-1)......` which quotient gives an answer with units of mass as required.......

`~=5.5*g`....... Do you agree?