Question

Hydrochloric acid is usually purchased in a concentrated form that is 37.0% HCl by mass and has a density of 1.20 g/mL. How much concentrated solution would you take to prepare 2.75 L of 0.460 M HCl by mixing with water?

Answer 1

To solve this problem we have to calculate the molarity of stock HCl solution. Then we can calculate the required volume of the concentrated solution to make a dilute solution.

37% HCl solution by mass means 37g of HCl are present in 100g of the solution

Volume of 100g of solution = mass / density = 100 / 1.2 = 83.33mL

In other words 37g of HCl is present in 83.33 mL of solution

37g of HCl = 37/36.5 = 1.013 moles of HCl., Because mlar mass of HCl = 36.5g

So 1.013 moles of HCl are present in 83.33mL of solution

Molarity = (No. of moles of solute / Volume of solution mL) X 1000

Molarity = (1.013 / 83.33) X 1000 = 12.1M

Use M1V1 = M2V2 equation to calculate the volume of concentrated solution to make dilute solution

M1 = 12.1M, V1 = ?, M2 = 0.460M, V2 = 2.75L

12.1M X V1 = 2.75 X 0.46M

V1 = 0.1045L = 104.5mL