How to calculate mass in grams of Avogadro's number of Cu atoms

Question

I have calculated 63.54/6.02 x 10^-23 and get the answer 10.55 x 10^-23, not sure if this is correct? 

Answer 1

What you have calculated is the mass in grams of 1 Cu atom, not Avogadro's number of Cu atoms.  Avogadro's number of Cu atoms is equivalent to 1 mole of Cu atoms = 63.54 grams.  Look at it this way...

1 atom Cu x 1 mole Cu/6.022x10²³ atoms Cu x 63.546 g Cu/1 mole Cu = 1.055x10^-22 g Cu in 1 atom of Cu which is what you have calculated.  NOTE: 10.55x10^-23 is the same as 1.055x10^-22.

Answer 2

The mass of Avogadro's number of copper atoms is going to be equal to copper's molar mass, which cn be found either online or on a periodic table.

Mass = 6.022 x 10^23 atoms x (1 mol / 6.022 x 10^23 atoms) x 63.55 g / 1 mol = 63.55 g Cu