chemistry question?

Question

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

Answer 1

This is an easy question.
first convert the gram wt to moles (g/g per mole)=moles
Then multiply the moles by 6.022 X10 raised to the 23. This equals the amount of atoms in that sample.

Answer 2

You need to change g to moles to molecules then to atom

12.0 g Cu x 1mol/63.54g Cu x 6.02x10^23 molecules/1mole x 1 atom/1molecule = 1.14 x 10^22 atom

It's only one atom because it's only copper, however if it's O2 you have to multiply by 2atom instead of 1 because there 2 O.

Answer 3

Since it is asking for atoms, you need to use Avogadro's number; you also need the mass of one mole of copper (look on periodic table)

12g --> moles/g --> Avo's number of atoms of Cu/mole --> your answer