Question

What will be the normality of a solution containing 4.9g of H3PO4 dissolved in 300ml
water is
1) 0.3 2)1.0 3)3.0 4)0.1​

Answer 1

Answer:

1) 0.3

Explanation:

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

=0.05mol

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

= 0.05 ÷ 0.5

= 0.1M

we know,

normality = n − factor × molarity

so,normality = 3 × 0.1

= 0.3N