Determination of equivalent weight of metal by oxide formation method

This method is used to find out the equivalent mass of those metals (Magnesium, Zinc) which can easily form their oxides.

2Mg + O2 ? 2MgO

Procedure:
? A known mass of a metal (m1) is heated in air or oxygen.
? The mass of metal oxide (m2), formed is found.
? In some cases (Cu, Pb, Sn etc.,) first the metal (m1) is converted into its salt.
? Then the metallic salt is converted into its oxide by heating the salts.
? Because the metals could not be directly converted into their oxides.
? The mass of metal oxide formed is found (m2).
? From the mass of metal oxide and the mass of metal, the mass of oxygen that has combined with the metal is found.
? The mass of oxygen that has combined with the metal = m2 – m1
? (m2 – m1) g of oxygen has combined with = m1g of metal
m1
8g of oxygen will combine with = --------- x 8
m2 – m1
By definition it refers to the equivalent mass of the metal.

Mass of metals
Equivalent mass of the metal = ------------------------------------------------------- x 8
Mass of oxygen that has combines with m1