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

The next answer is the number of moles of 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

2nd answer

  9.63 x 1023

Solution:

To determine the molar mass of Cr2O3 the atomic mass of each of the elements in the formula must be obtained from the periodic table. The atomic masses are;

Cr 52.0 u

O 16.0 u

Since there are 2 hydrogen atoms and 4 oxygen atoms in the formula the molecular mass is;

Cr 2 x 52.0 u = 104 u

O 3 x 16.0 u = 48.0 u

Total = 152 g­mol-1