Q.6:- 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%.
Mass percent of 69% means tat 100g of nitric acid solution contain 69 g of nitric acid by mass.
Molar mass of nitric acid (HNO3) = 1+14+48 = 63g mol-1
Number of moles in 69 g of HNO3 = 69/63 moles = 1.095 moles
Volume of 100g nitric acid solution = 100/1.41 mL = 70.92 mL = 0.07092 L
∴ Conc. of HNO3 in moles per litre = 1.095/0.07092 = 15.44 M