**Equivalent Mass of Divalent Metal Element**

The equivalent mass of a substance is the mass of the substance that reacts with or replaces one mole of hydrogen ions (H+) or hydroxide ions (OH-) in a chemical reaction. In the case of a divalent metal element, it refers to the mass of the metal that reacts with or replaces two moles of H+ or OH- ions.

To calculate the equivalent mass of a divalent metal element, we need to determine the number of moles of the metal that reacts with two moles of H+ or OH- ions. The molar mass of the metal can then be divided by this number of moles to obtain the equivalent mass.

**Molar Mass of Anhydrous Oxide**

The molar mass of an anhydrous oxide is the mass of one mole of the oxide compound without any water molecules. In the case of a divalent metal oxide, it refers to the mass of the oxide compound that contains one mole of the metal element and one mole of oxygen.

To calculate the molar mass of the anhydrous oxide, we add up the atomic masses of the metal element and the oxygen atom. The atomic masses can be obtained from the periodic table. The molar mass is expressed in grams per mole.

**Explanation**

1. Determine the atomic mass of the divalent metal element from the periodic table. Let's assume it is M grams per mole.
2. Since the metal is divalent, it reacts with or replaces two moles of H+ or OH- ions. Therefore, the number of moles of the metal that react with two moles of H+ or OH- ions is 1 mole.
3. The equivalent mass of the divalent metal element is then given by:

Equivalent mass = M grams per mole / 1 mole

4. Determine the atomic mass of the oxygen atom from the periodic table. Let's assume it is O grams per mole.
5. Since the anhydrous oxide contains one mole of the metal element and one mole of oxygen, the molar mass of the anhydrous oxide is given by:

Molar mass of anhydrous oxide = (M + O) grams per mole

**Example**

Let's consider the divalent metal element as calcium (Ca) with an atomic mass of 40 grams per mole. The equivalent mass of calcium would be:

Equivalent mass = 40 grams per mole / 1 mole = 40 grams per mole

Now, let's assume the atomic mass of oxygen is 16 grams per mole. The molar mass of the anhydrous oxide, calcium oxide (CaO), would be:

Molar mass of CaO = (40 + 16) grams per mole = 56 grams per mole

Therefore, the equivalent mass of the divalent metal element is 40 grams per mole, and the molar mass of its anhydrous oxide, calcium oxide, is 56 grams per mole.

Divalent metal MO2
eq mass = molar mass/ equivalent factor
molar mass= 10×2=20
therefore (20+16×2)= 52