Question

Calculate the concentration of nitric acid in moles per litre in a sample which has a density, 1.41 g mL–1 and the mass per cent of nitric acid in it being 69%.

Answer 1

Solution: We have

Mass percent of HNO₃=69%

Hence mass of HNO₃ in the solution is 69g

Mass of water=100-69=31g

Number of moles of HNO₃ =69/63=1.09moles

Density=mass/volume

Volume=mass/density

  =100/1.41=70.9ml

Concentration (Molarity) = number of moles of solute/volume of the solution

   = (1.09/70.9)×100

  = 1.5M