Chapter 2, Problem 97E

Interpretation Introduction

Interpretation:

Estimate the number of atoms in the universe.

Concept introduction:

Volume of sphere with radius r is

$V=\frac{4}{3}\pi r^3$

Density of a substance is defined as the ratio of mass and volume.

$\text{Density}=\frac{\text{mass}}{\text{volume}}$

Rearranging the above, mass can be calculated as the product of density and volume.

$\text{Mass}=\text{density }\times \text{volume}$

Number of moles can be calculated as

$\text{Number of moles =}\frac{\text{mass}}{\text{molecular mass}}$

One mole of substance contains $6.022\times {10}^{23}$ atoms.