Testing Methods of Hydrochloric Acid | Hydrochloric Acid Testing Procedure

Hydrochloric acid (HCl) purity and concentration can be determined using titration methods.

>DETERMINATION OF ASSAY OF CAUSTIC SODA (NaOH)

APPARATUS

a). 5 ml stoppered weighing bottle.

b). 100 ml conical flask.

c). 10 ml pipette.

d). Burette.

e). Nessler measuring cylinder

REAGENTS

a). Standard 1 (N) NaOH solution.

b). Methyl Red indicator.

ASSAY PROCEDURE OF HCL

Take a hydrochloric acid sample in a 5 ml weighing bottle. 

Carefully transfer about 1 gm (weighing accurately) into a 100 ml conical flask containing 10 ml distilled water. 

Titrate with 1(N) sodium hydroxide solution taken in burette using methyl red as an indicator. 1 ml of 1(N) sodium hydroxide = 0.03646 gm. HCl.

Assay of HCL (%) = Titre value (ml) x normality NaOH x 3.646/Weight of HCl sample taken (gm).

Molar Mass of Hydrochloric Acid

The molar mass of hydrochloric acid (HCl) is 36.46 g/mol. 

It is calculated by adding the atomic masses of hydrogen (1.008 g/mol) and chlorine (35.45 g/mol).

1.008 g/mol + 35.45 g/mol = 36.46 g/mol.

>DETERMINATION OF THE STRENGTH OF FORMALDEHYDE (FORMALIN)

How can the analysis of iron percentage in HCL solution be?

Determination of Iron In HCL: Take the Sample in a Conical Flask. Add a pinch of APS (Ammonium persulphate) and boil well and cool. then add 10.0ML of 10% KCNS 
( Potassium thiocyanate) Solution.

Developers the red color due to the formation of ferric thiocyanate. Transfer the solution into a 100 ML Nessler measuring cylinder and makeup.
This Red color is comparable with the red color produced by the known volume of STD iron solution.

Percentage of Iron (%) =(V1x0.1x100)/(VxSp.Gv.x1000)
iron conc. (as Fe)

Where 

1.0 ml Std. iron solution = 0.1 mg of iron
V1= Volume of standard iron solution used
V= Volume taken from HCL sample

Analysis of Free Chlorine Percentage in HCL?

Determination of free chlorine in HCL: Take 24.0 ml of HCL sample into a conical flask and add 50.0 ml of chlorine-free distilled water. And titrate with 0.1 % methyl orange indicator till permanent red color.

% by mass of free chlorine = (Vx18)/Sp.Gv. *10000

V= Volume of methyl orange used for 24.0 ml of HCL sample.