The mass of a single tungsten atom is 3.05×10-22 grams. How many tungsten atoms would there be in a sample of tungsten with a volume of 250 cm3 if the density of tungsten is 19.4 g/cm3?

Answer 1

Hi John!

Recall the the equation for density is

ρ = M / V

where ρ is density, M is mass, and V is volume.

In this problem, we are given both the density and the volume. Before finding out how many atoms there are in the sample, we first need to find the sample's mass.

Rearranging the density equation, we have

M = ρ * V

So the mass is

M = 19.4 * 250 = 4850 g

Now, according to the problem statement, the mass of one atom of tungsten is m_W = 3.05 * 10^-22 g. So to find the total number of tungsten atoms in the sample, N, we just divide the mass of the sample by the mass per atom of tungsten.

N = M / m_W = 4850 / (3.05 * 10^-22) = 1.59 * 10²⁵ atoms of tungsten.