How many atoms of cobalt would there be in a 2.2-gram sample of cobalt?

4.64 x 1021 atoms

2.25 x 1022 atoms

1.61 x 1025 atoms

7.81 x 1025 atoms
@ganeshie8

Question

How many atoms of cobalt would there be in a 2.2-gram sample of cobalt?

 4.64 x 1021 atoms

 2.25 x 1022 atoms

 1.61 x 1025 atoms

 7.81 x 1025 atoms
@ganeshie8

ganeshie8 · Answer

http://www.chemicool.com/elements/cobalt.html

lovelyharmonics · Answer

wouldnt it be b?

ganeshie8 · Answer

atomic weight of cobalt $\approx $ 59

ganeshie8 · Answer

that means there are $\large 6.022 \times 10^{23}$ atoms in $\large  59 ~grams$ of cobals

ganeshie8 · Answer

$$\large \dfrac{6.022\times 10^{23}}{59} = \dfrac{x}{2.2}$$

lovelyharmonics · Answer

2.2 grams/(58.9g/mole)=0.0374mole 
6.023 x 10^ 23 atoms / mole 

0.0374 moles (6.023 x 10^23 atoms/mole)=2.25 x 10^22 atoms of cobalt.

ganeshie8 · Answer

$$\large x = \dfrac{6.022\times 10^{23}}{59}\times 2.2  $$

ganeshie8 · Answer

http://www.wolframalpha.com/input/?i=6.022*10%5E23*2.2%2F59

ganeshie8 · Answer

b is right !