Question

3. The mass of H2SO4 needed to prepare 1 litre of 0.2 N solution is
(A) 4.9 g
(B) 9.8 g
(C) 17.6 g
6
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Answer 1

Answer:To prepare 5N H2SO4 245 grams of the pure acid is needed. The density of this pure acid is 1.84 grams per mL.

Explanation: The normality of a solution is the concentration expressed as the number of equivalent weights (equivalents) of solute per liter of solution. A 1 normal (1 N) solution contains 1 equivalent weight of solute per liter of solution.

The equivalent weights of solute per liter of solution is 2 since in i mole of sulfuric acid there are 2 moles of hydronium ions. To prepare 5N solution of H2SO4 we need 2.5 moles of H2SO4 for every 1 liter of the solution.

A one molar solution has a mass of (H = 2 g; S = 32 g; O = 64 g) 98 grams. A 2.5 molar solution we need 98 g times 2.5 = 245 grams of H2SO4.