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

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

#### Solution

Mass percent of nitric acid in the sample = 69 % [Given]

Thus, 100 g of nitric acid contains 69 g of nitric acid by mass.

Molar mass of nitric acid (HNO3)

= {1 + 14 + 3(16)} g mol–1

= 1 + 14 + 48

= 63 g mol–1

∴ Number of moles in 69 g of HNO3

=(69g)/(63g" mol"^-1)

= 1.095 mol

Volume of 100g of nitric acid solution

="Mass of solution"/"Density of solution"

=(100 g)/(1.41 g" mL"^-1)

=70.92" mL"-=70.92 xx 10^-3 L

Concentration of nitric acid

=(1.095" mole")/(70.92xx10^-3L)

= 15.44 mol/L

∴ Concentration of nitric acid = 15.44 mol/L

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