Question

A sports medal has a total surface area of 150 cm^2. It was evenly coated with silver by

electrolysis. Its mass increased by 0.216g. How many atoms of silver were deposited per cm^2 on the surface of the medal?

A. 8.0 × 10^18
B. 1.8 × 10^19
C. 8.7 × 10^20
D. 1.2 × 10^21

Answer 1

A.8.0×10^18

Step-by-step explanation:

atomic weight of silver = 107.8682 g/mol

0.216g / 107.8682 g/mol = 0.002 moles of silver in your sports medal

There are 6.02 * 10^23 atoms/mole in a mole of anything (Avogadro number)

0.002 mol * (6.02 * 10^23 atoms/mole) = 1.205 * 10^21 atoms of Ag in your sample

Divide by 150 to get per square centimeter:

= 8.033 * 10^18 silver atoms per square cm