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HCL titration analysis

Q. Hi,
I need help with this, I have a 70 gals tank contain 30% HCl and DI water balance.I need to do a titration analysis to determine acid concentration to see how much acid addition I need for each week to maintain concentration. Can you show me how to do this type of calculation I am looking for titration data.

Thanks in advance.

Calvin Nguyen
plating shop - Houston, Texas
November 5, 2008

A. Hi Calvin,

In order to do the analysis for free hydrochloric acid you need:

1) 1.0N NaOH [1N NaOH on Amazon]
2) bromophenol blue [on eBay or Amazon] indicator solution

This indicator is water soluble and exhibits a color change during the 3.0-4.6 pH interval going from yellow to purple.

First prepare the indicator solution by dissolving about 0.5 g of the bromophenol blue reagent in about 400 ml of distilled water to which about 3 ml of 0.1N sodium hydroxide [on eBay or Amazon] has been added. This neutralizes the sulfonic acid group thus making the indicator soluble.

Then, to a clean 250 Erlenmeyer flask, pipet 25.0 ml of the solution to be analyzed. Add about 60 ml of distilled water and about 1 ml of the bromphenol indicator. Titrate to the blue with standard sodium hydroxide.

=>> ml NaOH X N NaOH X 0.529 = oz/gal hydrochloric acid, (37%) <<==

Hope this helps.

Martin Michel
- Bielefeld, Germany

? Calvin,

You do not state what strength of Hydrochloric Acid you are using. From you statement, I would presume that you are using 30% by volume of a certain strength industrial hydrochloric acid and you wish to be able to analyze this so that you may maintain the concentration. Is this correct?

Gene Packman
process supplier - Great Neck, New York

Multiple threads were merged: please forgive repetition, chronology errors, or disrespect towards other postings [they weren't on the same page] :-)

Q. I would like to know the method of finding out the concentration of the HCl in the pickling bath.

Normally when the iron removal rate is slow then we will change the acid. But would like to analyse the sample in lab for finding out the concentration percentage.
Please tell me the process

Thanks & Regards,

Ravi Shankar
- Chennai, Tamilnadu, India
March 26, 2009

A. Sir:
Titrate with a strong base and use an indicator that changes color at a low pH.
Regards,

Dr. Thomas H. Cook
Galvanizing Consultant - Hot Springs, South Dakota, USA

Q. Hi sir
I work in a HDG plant, I'm a chemical engineer , I use the titration of HCl by NaOH to determine the HCl concentration in the pickling bath, but after a time the HCl conc. decrease and the FeCL2 increase, so by titration a dirty green precipitation formed (i think it is Fe(oH)2, so I can not get the titration end point
note:I repeat the titration with sod. carbonate and use a variety of reagents (ph. ph).methyl orange [on eBay or Amazon]
how can I overcome that problem
thanks sir

M Saad
chemical eng - Cairo, Egypt
April 17, 2009

A. Sir:
Take a smaller sample of acid and dilute it more with distilled water. Use an indicator which has a dramatic change in color and at a low pH. Use more indicator as needed. If you still have problems get an analytical chemistry text and follow the method.

Regards,

Dr. Thomas H. Cook
Galvanizing Consultant - Hot Springs, South Dakota, USA

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