Question

How many atoms are in 15.3 cm3 of mercury (at room temperature)?

Answer 1

Do you know the density?

Answer 2

Yes, its 15.546 g/mol

Answer 3

density if a measure of mass over volume

so you got your units wrong. it's supposed to be g/mL or g/cm^3 which is the same thing.

Answer 4

sorry, it's 13.546 g/cm3

Answer 5

First you convert the ml to g using the density as Aaron suggested. Then you convert the g to mole using the molar mass of Mercury. Then you use Avogadro's number to convert moles to number of atoms. I mole of anything has 6.022x 10^23 atoms