Determine the molarity of a solution of concentrated nitric acid.

Question

Determine the molarity of a solution of concentrated nitric acid. Concentrated nitric acid is 70% by mass HNO3. The density of concentrated nitric acid is 1.42 g/ml

Answer 1

Since molarity is defined as moles of solute per liter of solution, we need to find the number of moles of nitric acid, and the volume of solution.

molar mass of nitric acid (HNO3) = 1 + 14 + (3x16) = 15 + 48 = 63 g/mole

1.42 g/ml x 1000 ml = 1420 g/liter

1420 g/liter x 0.70 = 994 g/liter of pure HNO3 (the 0.7 is to correct for the fact that it is 70% pure)

994 g/liter x 1 mole/63 g = 15.77 moles/liter = 15.8 Molar HNO3