Question

A closed container has 7.05 ⋅ 1023 atoms of a gas. Each atom of the gas weighs 1.67 ⋅ 10-24 grams. Which of the following shows and explains the approximate total mass, in grams, of all the atoms of the gas in the container?

Answer 1

This can easily be solved using dimensional analysis – find a way to cancel out units. Since each atom weighs 1.67 x10^-24 grams, it could be written as: (1.67x10^-24 grams/atom)

Therefore

Total mass in grams of all atoms = (7.05 x 10^ 23 atoms)(1.67x10^-24 grams/atom) = 1.1774 grams