Copper is one of a group of metal called the coinage metals. How many atoms of copper are in a pure copper coin weighing 12.0 g?

1 Answer
Feb 3, 2016

Answer:

We need to (i) calculate the number of moles of #Cu#; and (ii) convert that molar quantity into a number.

Explanation:

#"Moles of copper"# #=# #(12.0*cancelg)/(63.55*cancelg*mol^-1)# #=# #0.189# #mol#.

Now in 1 mole of stuff there are #6.022xx10^23# individual items of that stuff. The mole is just a (large) number like a dozen, or a score, or a gross.

So all we have to do is to mulitply the molar amount by Avogadro's number:

#0.189# #cancel(mol)# #xx# #6.022xx10^23# #cancel(mol^-1)# #=# #??# #"copper atoms"#