Question

if a sample if pure sodium bas a mass of 8.2 grams and sodium has an average atomic mass of 22.99 g/mol, how many sodium atoms are there in the sample?

Answer 1

simple dimensional analysis:

8.2 grams * 1 mol / 22.99 grams * 6.02 x 10^23 atoms / mol = 2.1 x 10^23 atoms