Question

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 4.90 l of an hcl solution with a ph of 1.80?

Answer 1

(a) Calculate the molar concentration of the dil. HCl

[H+] = 10^(-pH) mol/L = 10^(-1.80) mol/L = 0.015 85 mol/L

(b) Calculate the mass of HCl in the dil. HCl

Moles of HCl = 4.90 L dil solution × (0.015 85 mol HCl/1 L dil solution)

= 0.077 66 mol HCl

MM of HCl = (1.008 + 35.45) g/mol = 36.458 g/mol

Mass of HCl = 0.077 66 mol HCl x (36.458 g HCl/1 mol HCl) = 2.831 g HCl

(c) Calculate the volume of conc. HCl

Mass of conc solution = 2.831 g HCl x (100 g conc solution/36.0 g HCl)

= 7.865 g conc solution

Volume of conc HCl

= 7.865 g conc solution × (1 mL conc HCl/1.179 g conc solution)

= 6.67 mL conc HCl