Question

How many atoms are found in a 15.5 g sample of bismuth?

Answer 1

Answer:

4.47 x 10²² atoms

Explanation:

Given parameters:

Mass of Bismuth  = 15.5g

Unknown:

Number of atoms  = ?

Solution:

To find the number atoms, first solve for the number of moles in this element first.

  Number of moles  = $\frac{mass}{molar mass}$    

  Number of moles  = $\frac{15.5}{209}$    = 0.074mole

So:

        1 mole of a substance contains 6.02 x 10²³ atoms

     0.074 mole of Bismuth will contain 0.074 x 6.02 x 10²³ atoms

                                                          = 4.47 x 10²² atoms