Question

Use the data table inside the front cover of Callister or another source of atomic weights and densities to answer this question. A silver wire is 0.4 mm in diameter and 12 cm long. How many atoms it contain?

Answer 1

The wire is cylinderical in shape .

The volume of wire is given as

null

So volume of the wire will be = 3.14 x (0.2)² x 120

= 15.086 cubic mm or 1.5086 x 10^-2 cubic cm

Density of silver is 10.49 g/cm³

Density = mass / volume

Mass = 10.49 x 1.5086 x 10^-2

Mass = 0.158 g

Molar mass of silver = 107.9 g / mol

So 0.158 g = 0.158 / 107.9 = 0.00146 mole

1 mole of Ag has 6.022 x 10²³ atoms

So number of atoms present in 0.00146 mole will be 0.00146 x 6.022 x 10²³

= 8.79 x 10²⁰ atoms