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

Answer:

Mass % of the solution = 7.1067 %

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.

$Molarity=\frac{Moles\ of\ solute}{Volume\ of\ the\ solution}$

Lets, consider the volume of the solution = 1 L

Thus,

Moles of nitric acid present in the solution:

$Molarity=\frac{Moles\ of\ solute}{Volume\ of\ the\ solution}$

$Moles of Nitric acid=Molarity \times {Volume\ of\ the\ solution}$

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:

$moles=\frac{Mass\ taken}{Molar\ mass}$

Thus,  

$Mass\ of\ Nitric\ acid=Moles \times Molar mass}$

$Mass\ of\ Nitric\ acid=1.85 g \times 63 g/mol}$

Mass of Nitric acid = 116.55 g

Also,

$Density=\frac{Mass}{Volume}$

Given : Density = 1.64 g/mL

Also, 1 L = 10³ mL

Volume of the solution is 1000 mL

So, mass of the solution:

$Mass\ of\ the\ solution=Density \times {Volume\ of\ the\ solution}$

$Mass\ of\ the\ solution=1.64 g/mL \times {1000 mL}$

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:

$Mass \% =\frac{Mass\ of\ the\ solute}{Mass\ of\ the\ solution} \times {100}$

So,

$Mass \%=\frac{116.55}{1640} \times {100}$

Mass % = 7.1067 %