Two oxides of a metal contain 27.6% and 30.0% of oxygen respectively. If the formula of the first oxide is M3O4, find that of the second.

Percentage of oxygen=27.6

Precentage of metal=100-27.6=72.4

Formula of the metal oxide=M3O4

Let the atomic mass of the metal= x

Percentage by weight of the metal in the oide M3O4=3x *100/3x+64=72.4

3x=0.724*3x+0.724*64

0.828x=46.336

x=56

The atomic mass of the metal=56

 

Element      Precentage      Atomic Mass     Atomic ratio    Simplest ratio       whole no.ratio

M                70                  56                   70/56=1.25    1.25/1.25=1          2

O                30                  16                    30/16            1.88/1.25=1.5       3

 

M₂O₃