I have set up the following problem so you will have a chance to do it before seeing the answers and how the answers are calculated. Try answering each of the cells in the indicated order and then check to see if you understand the problem.

 

Formula

M , Molar Mass

(g­mol-1)

mass of sample

(g)

n, number of

moles of sample

N, number of atoms,

molecules or formula units

Cr2O3

1st answer

 

  9.63 x 1023

In this particular case either the molar mass or the number of moles of sample can be calculated first. Let's go ahead and do the molar mass first. Try to determine the correct molar mass of Cr2O3 before clicking on the link.