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 4.80 L of an HCl solution with a pH of 1.9

Answer 1

Answer:

5.195 ml

Explanation:

Dissociation of HCl yields;

HCl(aq)   ⇄   H⁺(aq)     +    Cl⁻(aq)

∴ [HCl] = [H⁺] = [Cl⁻]

pH = 1.9

= -log[ H⁺]

= $10^{-pH}$

= $10^{-1.9}$

= 0.01258 M

Moles of HCl = number of mole × volume

= 0.01258 × 4.80 L

= 0.06042 mole

Mass of HCl = number of moles of HCl  ×  Molar mass of HCl

Mass of HCl = 0.06042 mol ×  36.5 g/mol

Mass of HCl = 2.205 grams

Also, given that the density =  1.179 g/mL

Mass of HCl in the solution = 36% of the density

i.e $\frac{36}{100}*1.179$

= 0.4244 grams

Volume of a concentrated HCl solution needed can now be determined as;

= $\frac{2.205}{0.4244}$

= $5.195 ml$