**Equivalent Weight of H3PO4 in Reaction 1:**

In the reaction H3PO4 + OH- → H2PO4- + H2O, the equivalent weight of H3PO4 can be determined by analyzing the stoichiometry of the reaction.

1. Write the balanced chemical equation:
H3PO4 + OH- → H2PO4- + H2O

2. Determine the moles of H3PO4 and OH- involved in the reaction:
From the balanced equation, we can see that one mole of H3PO4 reacts with one mole of OH-. So, the moles of H3PO4 and OH- are equal.

3. Calculate the molar mass of H3PO4:
H3PO4 has a molar mass of 98 g/mol (1 hydrogen atom: 1 g/mol, 3 oxygen atoms: 48 g/mol, 1 phosphorus atom: 31 g/mol).

4. Calculate the equivalent weight of H3PO4:
The equivalent weight is the molar mass divided by the moles involved in the reaction. Since the moles of H3PO4 and OH- are equal, we can use either one to calculate the equivalent weight.

Equivalent weight = Molar mass / Moles
Equivalent weight = 98 g/mol / 1 mol
Equivalent weight of H3PO4 = 98 g/mol

**Equivalent Weight of H3PO4 in Reaction 2:**

In the reaction H3PO4 + 2OH- → HPO4^2- + 2H2O, the equivalent weight of H3PO4 can be determined using the same steps as in Reaction 1.

1. Write the balanced chemical equation:
H3PO4 + 2OH- → HPO4^2- + 2H2O

2. Determine the moles of H3PO4 and OH- involved in the reaction:
From the balanced equation, we can see that one mole of H3PO4 reacts with two moles of OH-. So, the moles of H3PO4 are half of the moles of OH-.

3. Calculate the molar mass of H3PO4:
H3PO4 has a molar mass of 98 g/mol (1 hydrogen atom: 1 g/mol, 3 oxygen atoms: 48 g/mol, 1 phosphorus atom: 31 g/mol).

4. Calculate the equivalent weight of H3PO4:
The equivalent weight is the molar mass divided by the moles involved in the reaction. Since the moles of H3PO4 are half of the moles of OH-, we can use the moles of OH- to calculate the equivalent weight.

Equivalent weight = Molar mass / Moles
Equivalent weight = 98 g/mol / (2 mol OH-)
Equivalent weight of H3PO4 = 49 g/mol

**Explanation:**

The equivalent weight of a substance is the amount of that substance that can donate or accept one mole of electrons or react with one mole of another substance. In both reactions mentioned, H3PO4 is involved in an acid-base reaction with OH-. The equivalent weight of H3PO4 is determined by considering the stoichiometry of the reaction and calculating the molar mass divided by the number of moles involved.

In Reaction

First answer

The equivalent Weight of H3PO4 in the reaction:Ca(OH)2 + H3PO4 = CaHPO4 + 2H2O.


second answer

Equivalent weight of CA(OH)2 would be, the total mass of the compound divided by no. Of electrons gained or lost in the reaction. So here it is 2 thus the eqv. Wt would be 74/2 =32.


third answer

Equivalent weight stands for Molecular weight/N factorN factor means H+ or OH- exchange in case of acid and bases respectively and in case of salts it is charge on cationnow , in given Question mass of H3PO4 is 98 and N factor is 2 as 2H are donatedso equivalent weight is 98/2= 49.

four answer

Molecular mass of H₃PO₄ = 3(1) + 31 + 4(16)
= 3+31+64
= 98

We know,

Equivalent weight = molecular mass/no.of replaceable hydrogens
Equivalent weight of H₃PO₄ = 98/3
= 32.6