How many grams of dibasic acid (mol.wt.200) should be present in 100 mL. of an aqueous solution to give decinormal strength

Options

(a) 1 g
(b) 10 g
(c) 2 g
(d) 20 g

Correct Answer:

1 g

Explanation:

Normality = Number of g. equivalents of solute / volume of solution (L).
Number of equivalents = Weight / Equivalent weight.
For dibasic acid, equivalent weight = molecular wt/2 = 200/2 = 100.
Volume of solution = 100 mL = 0.1 L. Normality = 0.1 N.
Weight of solute = equivalent weight ⨯ normality ⨯ volume of solution (L) = 100⨯ 0.1 ⨯ 0.1 = 1 g.