QUESTION 2.4
Concentrated nitric acid used in laboratory work is 68%68\%68% nitric acid by aqueous solution. What should be the molarity of such a sample of the acid if the density of the solution is 1.504 g mL−1mL^{-1}mL−1 ?
68% HNO3 by mass means
Mass of nitric acid = 68 g
Mass of solution = 100 g
Molar mass of HNO3=(1)+(14)+(16×3)=63 g mol−1
Number of moles of HNO3(nHNO3)=WM=(68 g)(63 g/mol)=1.079 mol
Density of solution =1.504 g mL−1
Volume of solution =MassDensity=(100 g)(1.504 g mL−1)
=66.5 mL or 0.0665 L
Molarity =Moles of soluteVolume of solution in litres
=(1.079 mol)(0.0665 L)
=16.23 mol L−1 or 16.23 M