Question

What is the mass of 5.31×1021 platinum atoms?

Answer 1

Avogadro's number represents the number of units in one mole of any substance. This has the value of 6.022 x 10^23 units / mole. This number can be used to convert the number of atoms or molecules into number of moles. We calculate as follows:

 5.31×10^21 platinum atoms ( 1 mol / 6.022 x 10^23 atoms ) ( 78 grams / 1 mol ) = 0.6878 grams platinum

Answer 2

Answer: 1.72 g

Explanation:

1) The atomic mass of an element is the mass of one mole of atoms.

2) One mole of atoms is 6.022×10²³ atoms (Avogadro's number).

3) The atomic mass of platinum is 195.078 grams / mole (from a periodic table)

4) Formulas:

number of moles = number of atoms / 6.022×10²³

mass in grams = number of moles × atomic mass

5) Calculations:

number of moles = 5.31×10²¹ atoms / 6.022×10²³ atoms/mole = 0.00882 moles

mass in grams = 0.08882 mol × 195.078 g/mol = 1.72 g