stp of Analysis of Hydrochloric acid


stp of Analysis of Hydrochloric acid


1.1 To lay down a procedure for Analysis of Hydrochloric acid.

2.1 This procedure is applicable to the Analysis of Hydrochloric QC lab

3.1 Q.C- Chemist

4.1 Head-Quality Assurance

5.0 DEFINITION: – Hydrochloric acid contains NLT 35.0 % w/w and NMT 38.0 % w/w of Hydrochloric acid calculated on the anhydrous basis.

6.0 Description: – A clear colourless, fuming liquid, odour, pungent.

7.0 Identification: –
Test of chloride —  silver nitrate  solutions of chlorides yield a white, curdy precipitate that is insoluble in nitric acid but is soluble in a slight excess of 6 N ammonium hydroxide.


8.0 Heavy metals: – Evaporate 3.5 ml on a steam bath to dryness, add 2 ml of 1N nitric acid to the residue, then dilute with water to 25 ml

(NMT 5ppm)

9.0 Bromide Or Iodide :-Dilute 1 ml with 2 volume of water Add 1 ml of chloroform to 10 ml of the dilution, and cautiously add, dropwise,    with constant agitation, chlorine TS that has been diluted with an equal volume of water; the chloroform remains free from even a transient     yellow, orange or violet colour

10.0 Free Bromine or Chlorine: – Dilute 1ml with 2 volume of water. add 1 ml of potassium iodide TS and 1ml of chloroform to 10ml of

the   dilution and agitate the mixture; the chloroform remains free any violet coloration for at least 1 minute.

11.0 Sulfate: – Dilute 1 ml with 2 volume of water. To a mixture of 3 ml of the dilution and 5 ml of water add 5 drops of barium chloride TS.

Neither turbidity nor precipitate appears within 1 hour.

12.0 Sulfite: – Dilute 1 ml with 2 volume of Water. On the completion of the test of sulfate, the addition to the liquid of 2 drops of 0.1N iodine

produce neither turbidity nor decolonization of iodine.

13.0 Residue On Ignition: -20 ml add 2 drops of sulfuric acid, evaporate to dryness and ignite: not more than 2 mg of residue remains


Calculation: –

                      Wt. of Empty crucible (A), Wt. of crucible &Sample (B), Wt. of Sample C

After evaporation wt. of crucible & Sample (D)




—          (D-A) X 100

% Residue on Ignition:     = —————–

–              (B-A)




 14.0Assay: –                                                                                     NLT 35.0 % w/w and NMT 38.0 %w/w

                  Place about 3ml of Hydrochloric Acid in glass- stoppered flask, previously tared while containing about 20 ml of water and weigh of the substance under assay. Dilute with about 25 ml of water, add methyl red solution, and titrate with 1N Sodium hydroxide solution (Each ml of 1N sodium hydroxide solution is equivalent to 34.46 mg of Hcl.


Each ml of 1 M sodium hydroxide, is equivalent to 36.46 mg of Hydrochloric acid. (HCL).


V= Volume (in ml) of sodium hydroxide acid consumed in titration.

N = Actual normality of sodium hydroxide Solution.

Wt.  = Weight of Sample.

Calculation: –        

                            –           V X N X Factor X100

                                  –    0.1 X Sample Weight



Sr. No. Abbreviation used Full form of abbreviation used
1.0 STP Standard Testing Procedure
2.0 QA Quality assurance
3.0 STD Standard
4.0 SPL Sample


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