3. Commercial phosphoric acid, H3PO4, is often purchased as a 85.5 weight percent solution. Find the mg/L of H2SO4 and the molarity and normality of the solution. The concentrated sulfuric acid solution has a density of 1.71 g/ml at the temperature of the system.

The answers to the question are

(a) The the mg/L of H₃PO₄is 1462.05 g

(b) The molarity  of H₃PO₄ in the solution is 14.92 mol/L

(c) The normality of H₃PO₄ in the solution 44.85 eq/L

Explanation:

(a) The commercially available H₃PO₄ has a concentration of 85.5 percent by weight, therefore

The mass of H₃PO₄ is found by

Density of water = 1.71 g/ml

mass of one liter of acid solution = 1.71 ×1000 = 1710 g

Therefore 85.5 % by weight of H₃PO₄ =1710×85.5/100 = 1462.05 g

Therefore we have 1462.05 g/L of H₃PO₄

Molar mass of H₃PO₄ = 97.994 g/mol

(b)Therefore the number of moles in 1462.05 g = 14.92 moles and the molarity = 14.92 mol/L

(c) The Normality =  = 1465.05÷(1×97.994/3) = 44.85 eq/L