Question

The density of an aqueous solution of nitric acid is 1.64 g/mL and the concentration is 1.85 M. What is the concentration of this solution in percent by mass?

Answer 1

Mass % of the solution = 7.1067 %

Step-by-step explanation:

Given :

Molarity of nitric acid solution = 1.85 M

Density of the solution = 1.64 g/mL

Molarity of a solution is defined as the number of moles of solute present in 1 liter of the solution.

`Molarity=(Moles\ of\ solute)/(Volume\ of\ the\ solution)`

Lets, consider the volume of the solution = 1 L

Thus,

Moles of nitric acid present in the solution:

`Molarity=(Moles\ of\ solute)/(Volume\ of\ the\ solution)`

`Moles of Nitric acid=Molarity * {Volume\ of\ the\ solution}`

So,

Moles of Nitric acid = 1.85 moles

Molar mass of nitric acid = 63 g/mol

The mass of Nitric acid can be find out by using mole formula as:

`moles=(Mass\ taken)/(Molar\ mass)`

Thus,

`Mass\ of\ Nitric\ acid=Moles * Molar mass}`

`Mass\ of\ Nitric\ acid=1.85 g * 63 g/mol}`

Mass of Nitric acid = 116.55 g

Also,

`Density=(Mass)/(Volume)`

Given : Density = 1.64 g/mL

Also, 1 L = 10³ mL

Volume of the solution is 1000 mL

So, mass of the solution:

`Mass\ of\ the\ solution=Density * {Volume\ of\ the\ solution}`

`Mass\ of\ the\ solution=1.64 g/mL * {1000 mL}`

Mass of the solution = 1640 g

Mass % is defined as the mass of solute in 100 g of the solution. The formula for the calculation of mass % is shown below:

`Mass \% =(Mass\ of\ the\ solute)/(Mass\ of\ the\ solution) * {100}`

So,

`Mass \%=(116.55)/(1640) * {100}`

Mass % = 7.1067 %