Question

What will be the normality of a solution containing 4.9 g. H3po4 dissolved in 500 ml water

Answer 1

H3PO4 dissociates into 3H^+ and PO4³-.

so, n - factor of H3PO4 = 3

mass of H3PO4 = 4.9g/mol

molar mass of H3PO4 = 3 × 1 + 31 + 4 × 16 = 3 + 31 + 64 = 98g/mol

so, no of moles of H3PO4 = 4.9/98 = 0.1/2 = 0.05 mol

now , molarity = no of moles of H3PO4/volume of solution in Litre

= 0.05/(500/1000)

= 0.1 M

we know,

normality = n - factor × molarity

so, normality = 3 × 0.1 = 0.3N