How to Determine the Strength of HCl

Last Updated on 09/01/2021

How to Determine/Calculate the Strength of HCl

Rofiquzzaman Raju
Chittagong Textile Engineering College


Textile industry is a chemical based industry. Different types of chemicals and auxiliaries used in textile wet processing. Among those Hydrochloric Acid (HCl) widely used in different process of dyeing. In the textile industry, Hydrochloric Acid (HCl) is used to neutralise alkaline residues in cotton in the cleaning process immediately prior to bleaching. Determination of chemical strength of HCl is important for textile industry. It he strength of HCl is not proper then the every process on textile is not proper. Titration is the best method for determination of strength of HCl. In this method 0.1 N NaOH is used for titration.

strength test of hcl
Fig: Determine strength of HCl


  1. To know about how determined the strength of HCl.
  2. To know about the titration process.
  3. To know about the solution making.
  4. To know about the end point of this testing.


  1. Beaker
  2. Pipette
  3. Stirrer
  4. Graduate cylinder
  5. Electronic balance
  6. Burette


  1. HCl
  2. 0.1 N NaOH
  3. And Indicator (Phenolphthalein)

Determination of Strength of HCl:

4 ml HCl is taken

Then it is diluted with 500 ml water

From that solution 25 ml is taken

After that 2-3 drops of indicator is added

Then it is taken in Conical flask. Then this sample solution is treated with 0.1 N NaOH

End Point: The end point is determined when the permanent pink color solution stay.


Molecular equivalent weight of HCl = 36.5 gm
So, 1000 ml Molecular equivalent weight is 36.5
1 ml molecular equivalent weight is = 36.5/1000 = 0.0365 gm

In 500 ml water the amount of sample is 4 ml
So, 25 ml of water the amount of sample is = ( 4 X 25)/500 = 0.20

Normality of NaOH is 0.1 N
And volume used of KMnO4 is 24.5 & 25.6

Following formula used for determining strength of HCl:

strength test of hcl

Results and discussion:

Required Amount of NaOHStrength of HCl %
24.5 & 24.644.712 & 44.895
23.7 & 22.343.252 & 40.697
24 &  23.243.8 & 42.34
23.8 &  24.143.435 & 43.982
23.7 & 23.543.252 & 42.887

From above results, we can say that the strength of HCl of different persons results have been obtained near to 43.5% and my results is 44.712 & 44.895. We have done experiment manually so something can be inaccurate measurement of pipette or burette reading. And at last, we can say that the strength of HCl is 44%.

At last we can say that, how to determine the strength of HCl, is known by this experiment. Knowledge is gained from this experiment which is very helpful in our practical life.

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