Question

A concentrated HCl solution contains 37.0 % wt HCI . The density of the solution is 1.190 g/ml. What volume of this reagent should be diluted to 0.5 L to make 6 M HCI solution? Select one: a. 0.3 L b. 0.2 L C. 0.4L d. 0.5 L

Answer 1

1st calculate the initial concentration of HCl

Let volume of solution be 1 L

volume , V = 1 L

= 1*10^3 mL

density, d = 1.19 g/mL

use:

mass = density * volume

= 1.19 g/mL *1*10^3 mL

= 1.19*10^3 g

This is mass of solution

mass of HCl = 37.0 % of mass of solution

= 37.0*1190.0/100

= 440.3 g

Molar mass of HCl,

MM = 1*MM(H) + 1*MM(Cl)

= 1*1.008 + 1*35.45

= 36.458 g/mol

mass(HCl)= 440.3 g

use:

number of mol of HCl,

n = mass of HCl/molar mass of HCl

=(4.403*10^2 g)/(36.46 g/mol)

= 12.08 mol

volume , V = 1 L

use:

Molarity,

M = number of mol / volume in L

= 12.08/1

= 12.08 M

use dilution formula

M1*V1 = M2*V2

1---> is for stock solution

2---> is for diluted solution

Given:

M1 = 12.08 M

M2 = 6 M

V2 = 0.5 L

use:

M1*V1 = M2*V2

V1 = (M2 * V2) / M1

V1 = (6*0.5)/12.08

V1 = 0.2483 L

Answer: 0.2 L