Question

A sample of air contains 21.9ìg/m3 of beryllium dust. How many atoms of beryllium are present in a room with dimensions of 8 feet by 12.3 feet by 18.3 feet? Answer in units of atoms.

Answer 1

I would change feet to meters for all three dimensions, then L x W x H of the room (in meters) will give you the volume in cubic meters. volume x concn Be dust (the 21.9 something g/m^3) will give you grams Be dust. Divide by atomic mass to arrive at moles, then remember there are 6.022 x 10^23 atoms in a mole.