The concentration of commercially available concentrated nitric acid is 70.0 percent by mass, or 15.9 M. Calculate the density and molality of the solution.\

The density of the solution has been 1.43 g/ml. The molality of the solution has been 37.03 m.

Density can be defined as the mass of the solution per unit of volume. The density can be calculated as:

Where, D has been the density.

The molecular weight of nitric acid has been,

The mass of nitric acid has been,

The molarity of the solution has been given as,

The volume of the solution can be given as:

Substituting the values for density,

The density of the solution has been 1.43 g/ml.

The molality of the solution has been given by :

Where,  moles of the solute has been given as,

The mass of the solvent has been given as,

Substituting the values for calculating molality, m:

The molality of the solution has been 37.03 m.

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Density of solution = 1.43 g/mL

Molality → mol/kg = 37 m

Explanation:

The solute is HNO₃

Molar mass → 63 g/mol

70 % by mass → 70 g of solute / 100 g of solution

We convert the mass of HNO₃ to moles → 70 g / 63 g/mol = 1.11 moles

So let's apply molarity to find out the volume of our moles.

Molarity (M)  = mol/L →  mol / M  = L → 1.11  mol / 15.9 M = 0.070 L

This is the volume for solution. We can convert it from L to mL

0.070 L . 1000 mL / 1L = 70 mL

As the mass of solution = 100 g → Density = Mass/Volume

100g / 70 mL = 1.43 g/mL

Molality → mol of solute / kg of solvent

Solution mass = 100 g → Mass of solute + Mass of solvent

Mass of solvent = 30 g

We convert the mass of solvent from g to kg → 30 g . 1kg / 1000 g = 0.030 kg

Molality (mol/kg) → 1.11 mol / 0.030 kg = 37 m