<u>Answer:</u>
<u>For a:</u> The molarity of commercial HCl solution is 12.39 M.
<u>For b:</u> The molality of commercial HCl solution is 16.79 m.
<u>For c:</u> The volume of commercial HCl solution needed is 2.42 L.
<u>Explanation:</u>
We are given:
Mass % of commercial HCl solution = 38 %
This means that 38 grams of HCl is present in 100 grams of solution.
To calculate the volume of solution, we use the equation:

Density of HCl solution = 1.19 g/mL
Mass of solution = 100 g
Putting values in above equation:

To calculate the molarity of solution, we use the equation:

We are given:
Molarity of solution = ?
Molar mass of HCl = 36.5 g/mol
Volume of solution = 84.034 mL
Mass of HCl = 38 g
Putting values in above equation, we get:

Hence, the molarity of commercial HCl solution is 12.39 M.
To calculate the molality of solution, we use the equation:

Where,
= Given mass of solute (HCl) = 38 g
= Molar mass of solute (HCl) = 36.5 g/mol
= Mass of solvent = 100 - 38 = 62 g
Putting values in above equation, we get:

Hence, the molality of commercial HCl solution is 16.79 m.
To calculate the molarity of the diluted solution, we use the equation:

where,
are the molarity and volume of the concentrated solution
are the molarity and volume of diluted solution
We are given:

Putting values in above equation, we get:

Hence, the volume of commercial HCl solution needed is 2.42 L.