Question

It is found that 1.431 g of element X contains 7.509 × 1021 atoms. The atomic mass of X is?

Answer 1

1.431 g of element X=7.509 × 10^21 atoms

1 mole=6.02 x 10^23 atoms, so

7.509 × 10^21 atoms*(1 mole/6.02 x 10^23 atoms)=moles of element X


(moles of element X/1.431 g of element X)=(1 mole/ atomic mass), solve for atomic mass

atomic mass=(1.431 g of element X/moles of element X)

Answer 2

i got 114.5 is this right?

Answer 3

I don't get that answer but close.
7.509E21/6.022E23 = ?
molar mass = 1.431/? = 114.76 which I would round to 114.8 to four significant figures. Since the data is to four places I used an extra place in 6.022 number but that doesn't account for the slight difference. You may be reading your calculator at the first calculation and rounding too much.