In: Chemistry
What volume of a concentrated HCl solution, which is 36.0% HCl by mass and has a density of 1.179 g/mL, should be used to make 4.95 L of an HCl solution with a pH of 1.9?
Required pH is 1.9
then using formula [H+] = 1^(-pH)
[H+] = 10^-1.90
[H+] = 0.0125 mol / L
As HCl is a strong acid it dissociates
completely, giving [H+] = [HCl]
In 4.95L solution we require 4.95*0.0125 = 0.0618 mol
HCl
Molar mass HCl = 36.46 g/mol
0.0618 mol HCl = 0.0618*36.46 = 2.2532 g HCl
Our stock solution is 36.0% by mass that means 100g solution
contains 36.0g HCl.
Mass of solution that contains 2.2532 g HCl = 2.2532/36.0*100 =
6.258 g HCl stock solution.
Volume of stock solution = mass / density
Volume = 6.258/1.179
Volume = 5.307 mL of the stock HCl solution
required.