Calculate the concentration of nitric acid in moles per litre in a sample which has a density of 1.41 g/mL and the mass per cent of nitric acid in it being 69%

The density of the solution is 1.41 g/mL. 1000 g of the solution will have a volume = Mass/Density = 1000/1.41 = 709 mL.
The mass per cent of nitric acid is 69%.
Therefore, in 1000 g of the solution, the mass of nitric acid = (69/100) * 1000 = 690 g.
The molar mass of nitric acid (HNO3) is 1 + 14 + 3(16) = 63 g/mol.
The number of moles of nitric acid in 690 g = 690 g / 63 g/mol = 10.95 moles.
The volume of the solution containing 10.95 moles of nitric acid is 709 mL or 0.709 L.
Therefore, the concentration of nitric acid in moles per litre = 10.95 moles / 0.709 L = 15.45 mol/L.