##2.258 xx 10^24## molecules
We use Avogadro’s number of ##6.022xx10^23## molecules per mole to calculate the number of molecules from the number of moles represented by ##”165 g”## of carbon dioxide.
The gram-molecular weight of carbon dioxide can be calculated from the atomic weights for carbon and oxygen (two of them in ##”CO”_2##) given in a Periodic Table of the Elements.
##(“165 g CO”_2)/(“44.01 g/mol”) xx (6.022xx10^23 “molecules”)/”mol”##
##= mathbf(2.258xx10^24 “molecules”)##
