Check your answer...do you agree? Great if you do. If you do not check the Solution: below the table to see how the number of moles of Cr2O3 is calculated.

The next answer is the mass the sample. Try to determine the value before clicking on the link.

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

152

3rd answer

1.66

9.63 x 1023

Solution:

We are to calculate the number of moles in the sample. This is done by converting the number of formula units of Cr2O3 to moles using Avogadro's number. We can not use the molar mass in this case because we do not know the mass of the sample of Cr2O3.