Question

You have 20g of cobalt. How many atoms of cobalt is this?

Answer 1

Hi Brent
You need to know the molar mass of cobalt ( 58.933 g/mol)
Convert 20 g of cobalt to moles
Do this by multiplying the given mass by the molar mass 20g x 1mol/58.933 grams =.339 mol
Then, to determine the 3 of atoms, use Avogadro's number( 1 mol of any atom has 6.022 x 10^23 atoms)
You have .339 mol, so, 0.339 x 6.022 x 10^23= 2.04 x 10^23 ( or 2 x 10^23) if you want to use the correct number of sig figs.
Good luck....